ModAdd

#include <algorithm>
#include <cstdio>
#include <cstddef>
#include <cstdint>
#include <iostream>
#include <vector>

using std::cout;
using std::endl;
using std::ios;
using std::swap;
using std::vector;


vector<uint8_t> read_number() {
    vector<uint8_t> result;

    for (int c; (c = getchar()) != '\n' && c != EOF;) {
        result.push_back(c - '0');
    }

    return result;
}


int main() {
    ios::sync_with_stdio(false);

    vector<uint8_t> a = read_number();
    vector<uint8_t> b = read_number();

    if (a.size() < b.size()) {
        swap(a, b);
    }

    int64_t a_i = 0;
    int64_t b_i = (int64_t) b.size() - (int64_t) a.size();
    bool zero = true;

    while ((size_t) a_i < a.size()) {
        int result;
        if (b_i < 0) {
            result = (int) a[a_i];
        } else {
            result = (int) ((a[a_i] + b[b_i]) % 10);
        }

        if (result != 0 || !zero) {
            cout << result;
            zero = false;
        }

        a_i++;
        b_i++;
    }

    if (zero) {
        cout << 0;
    }

    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