ModAdd

#include <iostream>
#include <algorithm>
#include <cstdio>

using namespace std;

int main(int argc, char *argv[])
{
    string x, y;
    vector<int> res;

    getline(cin, x);
    getline(cin, y);

    int n = x.length();
    int m = y.length();

    int dif = abs(n - m);

    if (n < m) {
        x = string(dif, '0').append(x);
        n = m;
    } else if (n > m) {
        y = string(dif, '0').append(y);
        m = n;
    }

    for (int i = n - 1; i >= 0; --i) {
        int a = 0;
        int b = 0;

        a = x[i] - '0';
        b = y[i] - '0';

        if (a + b >= 10) {
            res.push_back(a + b - 10);
        } else {
            res.push_back(a + b);
        }
    }

    bool isZero = true;

    for (int i = res.size() - 1; i >= 0; --i) {
        if (res[i] != 0 || i == 0) {
            isZero = false;
        }

        if (res[i] == 0 && isZero) {
            continue;
        }

        cout << res[i];
    }

    cout << endl;

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED