Alien Invasion II

input/code.cpp: In function 'int main()':
input/code.cpp:15:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < luku.size(); i++) {
                     ~~^~~~~~~~~~~~~
input/code.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < luku.size(); i++) {
                     ~~^~~~~~~~~~~~~
input/code.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < luku.size()+1; i++) {
                     ~~^~~~~~~~~~~~~~~
input/code.cpp:37:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < luku.size()+1; i++) {
                     ~~^~~~~~~~~~~~~~~

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
 
int osm[100];
char tulos[100];
 
int main() {
    string luku;
    cin >> luku;
    
    int summa = 0;
    for (int i = 0; i < luku.size(); i++) {
        summa += luku[i]-'0';
    }
    int a = 6 - summa%3;
    tulos[0] = a + '0';
    cout << tulos[0];
    for (int i = 0; i < luku.size(); i++) {
        tulos[i+1] = luku[i];
        cout << luku[i];
    }
    cout << endl;
    
 
    
 
    int yli = 0;
    for (int i = 0; i < luku.size()+1; i++) {
        int x = (yli *10 + tulos[i]-'0')/3;
        osm[i] = x;
        yli = (yli *10 + tulos[i]-'0') - 3*x;
    }
    cout << 3 << " ";
    for (int i = 0; i < luku.size()+1; i++) {
        if (i == 0 && osm[i] == '0') continue;
        cout << osm[i];
    }
    cout << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED