Alien Invasion II

#include<iostream>
using namespace std;

int main() {
    string s;
    cin >> s;
    unsigned int sum = 0;
    for (const char& c : s) sum += c - '0';
    int rem = (3 - sum%3)%3;
    if (rem != 0) cout << rem;
    cout << s << endl << "3 ";

    int carry = rem;
    for (const char &c : s) {
      const int n = carry*10 + c - '0';
      cout << n / 3;
      carry = n%3;
    }
    cout << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED