diff --git a/ex01/Makefile b/ex01/Makefile
new file mode 100644
index 0000000..e2e614e
--- /dev/null
+++ b/ex01/Makefile
@@ -0,0 +1,43 @@
+NAME = RPN
+
+SRC = main.cpp RPN.cpp
+
+
+OBJ = $(SRC:.cpp=.o)
+
+CC = c++
+CFLAGS = -Wall -Wextra -Werror -std=c++98
+
+GREEN = \033[0;32m
+RED   = \033[0;31m
+RESET = \033[0m
+
+TOTAL := $(words $(SRC))
+COUNT = 0
+
+all: $(NAME)
+
+$(NAME): $(OBJ)
+	@rm -f .build_start
+	@$(CC) $(CFLAGS) $(OBJ) -o $(NAME)
+	@printf "\n$(GREEN)✔ Listo (100%%)\n$(RESET)"
+
+%.o: %.cpp
+	@if [ ! -f .build_start ]; then printf "$(GREEN)Compilando archivos...\n$(RESET)"; touch .build_start; fi
+	@$(eval COUNT = $(shell echo $$(($(COUNT)+1))))
+	@PERCENT=$$(($(COUNT)*100/$(TOTAL))); \
+	BAR=$$(printf "%0.s#" $$(seq 1 $$((PERCENT/5)))); \
+	SPACE=$$(printf "%0.s " $$(seq 1 $$((20-PERCENT/5)))); \
+	printf "\r  [$$BAR$$SPACE] %3d%% (%d/%d) $<     " $$PERCENT $(COUNT) $(TOTAL)
+	@$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	@printf "$(RED)Eliminando...\n$(RESET)"
+	@rm -f $(OBJ)
+
+fclean: clean
+	@rm -f $(NAME)
+
+re: fclean all
+
+.PHONY: all clean fclean re
diff --git a/ex01/RPN.cpp b/ex01/RPN.cpp
new file mode 100644
index 0000000..60a707a
--- /dev/null
+++ b/ex01/RPN.cpp
@@ -0,0 +1,108 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   RPN.cpp                                   :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: aortigos <aortigos@student.42malaga.com>    +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2026/04/24 12:37:09 by aortigos          #+#    #+#             */
+/*   Updated: 2026/04/24 12:37:09 by aortigos         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "RPN.hpp"
+
+//////////////////
+// Constructors //
+//////////////////
+
+RPN::RPN()
+{
+    // std::cout << "RPN default constructor called" << std::endl;
+}
+
+RPN::RPN(const RPN &other)
+{
+    *this = other;
+    // std::cout << "RPN copy constructor called" << std::endl;
+}
+
+RPN& RPN::operator=(const RPN &other)
+{
+    if (this != &other)
+    {
+        // Copy attributes here
+    }
+    // std::cout << "RPN copy assignment operator called" << std::endl;
+    return (*this);
+}
+
+RPN::~RPN()
+{
+    // std::cout << "RPN destructor called" << std::endl;
+}
+
+void    RPN::math(std::string data)
+{
+    std::istringstream  ss(data);
+    std::string         token;
+    int     nbr;
+
+    while (ss >> token)
+    {
+        if (isToken(token))
+        {
+
+            if (numbers.size() < 2)
+            {
+                std::cout << "Error." << std::endl;
+                return ;
+            }
+
+            int b = numbers.top();
+            numbers.pop();
+            int a = numbers.top();
+            numbers.pop();
+
+            if (token == "+")
+                numbers.push(a + b);
+            if (token == "-")
+                numbers.push(a - b);
+            if (token == "*")
+                numbers.push(a * b);
+            if (token == "/")
+                numbers.push(a / b);
+        }
+        else
+        {
+            char *endptr;
+
+            nbr = std::strtol(token.c_str(), &endptr, 10);
+            if (*endptr != '\0')
+            {
+                std::cout << "Error." << std::endl;
+                return ;
+            }
+
+            if (nbr >= 10)
+            {
+                std::cout << "Error." << std::endl;
+                return ;
+            }
+
+            this->numbers.push(nbr);
+        }
+    }
+    if (numbers.size() != 1)
+    {
+        std::cout << "Error." << std::endl;
+        return ;
+    }
+    std::cout << numbers.top() << std::endl;
+}
+
+bool    RPN::isToken(std::string token)
+{
+    return (token == "+" || token == "-" 
+            || token == "*" || token == "/");
+}
\ No newline at end of file
diff --git a/ex01/RPN.hpp b/ex01/RPN.hpp
new file mode 100644
index 0000000..4539ed2
--- /dev/null
+++ b/ex01/RPN.hpp
@@ -0,0 +1,36 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   RPN.hpp                                   :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: aortigos <aortigos@student.42malaga.com>    +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2026/04/24 12:37:09 by aortigos          #+#    #+#             */
+/*   Updated: 2026/04/24 12:37:09 by aortigos         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#ifndef RPN_HPP
+
+# define RPN_HPP
+
+# include <iostream>
+# include <stack>
+# include <sstream>
+# include <cstdlib>
+
+class RPN
+{
+    private:
+        std::stack<int> numbers;
+    public:
+        RPN();
+        RPN(const RPN &other);
+        RPN& operator=(const RPN &other);
+        ~RPN();
+
+        bool    isToken(std::string token);
+        void    math(std::string data);
+};
+
+#endif
diff --git a/ex01/main.cpp b/ex01/main.cpp
new file mode 100644
index 0000000..e9dae47
--- /dev/null
+++ b/ex01/main.cpp
@@ -0,0 +1,27 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   main.cpp                                           :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: aortigos <aortigos@student.42malaga.com    +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2026/04/24 12:37:45 by aortigos          #+#    #+#             */
+/*   Updated: 2026/04/24 12:57:54 by aortigos         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "RPN.hpp"
+using	std::cout;
+using	std::endl;
+
+int	main(int argc, char **argv)
+{
+	if (argc != 2)
+	{
+		cout << "Error." << endl;
+		return (1);
+	}
+
+	RPN	calc;
+	calc.math(argv[1]);
+}
\ No newline at end of file