参考答案：

#include<iostream>

using namespace std;

int main()
{
    int a;
    cin >> a;
    int t = a;
    int sum = 0;
    while (t)
    {
        sum = sum * 10 + t % 10;
        t /= 10;
    }
    cout << sum << endl;

    return 0;
}