1. Reverse String

#include <iostream>
#include <string>
#include <stack>

using namespace std;

int main() {
    string s;
    getline(cin, s);

    stack<char> chars;

    for (int i = 0; i < s.length(); i++) {
        chars.push(s[i]);
    }

    while (!chars.empty()) {
        cout << chars.top();
        chars.pop();
    }

    cout << endl;
    return 0;
}