A TIMES B!

input/code.cpp: In function 'int main()':
input/code.cpp:15:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |     for (int i = a.size()%size; i < a.size(); i += size) {
      |                                 ~~^~~~~~~~~~
input/code.cpp:19:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |     for (int i = b.size()%size; i < b.size(); i += size) {
      |                                 ~~^~~~~~~~~~
input/code.cpp:22:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |     for (int i = 0; i < A.size(); ++i) {
      |                     ~~^~~~~~~~~~
input/code.cpp:25:23: warning: comparison of integer expressions of...

#include <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <iomanip>

int main() {
    std::string a, b;
    std::cin >> a >> b;
    int size = 5;

    std::vector<long long> A, B, C;
    //std::cout << a.size() << std::endl;
    if (a.size()%size != 0) A.push_back(atoi(a.substr(0, a.size()%size).c_str()));
    for (int i = a.size()%size; i < a.size(); i += size) {
        A.push_back(atoi(a.substr(i, size).c_str()));
    }
    if (b.size()%size != 0) B.push_back(atoi(b.substr(0, b.size()%size).c_str()));
    for (int i = b.size()%size; i < b.size(); i += size) {
        B.push_back(atoi(b.substr(i, size).c_str()));
    }
    for (int i = 0; i < A.size(); ++i) {
        //std::cout << A[i] << " ";
    }
    for (int i = 0; i < B.size(); ++i) {
        //std::cout << B[i] << " ";
    }
    //std::cout << std::endl;

    long long A_idx = A.size()-1;
    C.resize(A.size()+B.size(), 0);

    while(A_idx >= 0) {
        long long B_idx = B.size()-1;
        while(B_idx >= 0) {
            long long result = A[A_idx] * B[B_idx];
            C[A_idx+B_idx] += result;
            //std::cout << A_idx <<  " " << B_idx << " " << result << std::endl;
            B_idx--;
        }
        A_idx--;
    }
    for (auto c : C) {
        //std::cout << c << " ";
    }
    //std::cout << std::endl;

    //std::cout << C.size() << " " << C[0] << std::endl;
    
    long long temp = 0;
    for (int i = C.size()-1; i >= 0; --i) {
        long long result = C[i] + temp;
        long long last_digits = result % (long long) std::pow(10, size);
        C[i] = last_digits;
        C[i-1] += result / (long long) std::pow(10, size);
    }

    if (C[0] == 0) std::cout << C[1];
    else {
        std::cout << C[0] << std::setfill('0') << std::setw(size) << C[1];
    }
    for (int i = 2; i < C.size(); --i) {
        std::cout << std::setfill('0') << std::setw(size) << C[i];
    }    
    
    std::cout << std::endl;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: RUNTIME ERROR

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 16

Verdict: RUNTIME ERROR

Test 17

Verdict: RUNTIME ERROR

free(): invalid size

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: WRONG ANSWER

Test 22

Verdict: RUNTIME ERROR

Test 23

Verdict: RUNTIME ERROR

Test 24

Verdict: WRONG ANSWER

Test 25

Verdict: WRONG ANSWER

Test 26

Verdict: WRONG ANSWER

Test 27

Verdict: RUNTIME ERROR

Test 28

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 29

Verdict: WRONG ANSWER

Test 30

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 31

Verdict: RUNTIME ERROR

Test 32

Verdict: RUNTIME ERROR

free(): invalid size

Test 33

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 34

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 35

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 38

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 39

Verdict: WRONG ANSWER

Test 40

Verdict: RUNTIME ERROR

Test 41

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 42

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 43

Verdict: RUNTIME ERROR

free(): invalid size

Test 44

Verdict: WRONG ANSWER

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: WRONG ANSWER

Test 47

Verdict: RUNTIME ERROR

Test 48

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 49

Verdict: WRONG ANSWER

Test 50

Verdict: WRONG ANSWER

Test 51

Verdict: RUNTIME ERROR

free(): invalid size

Test 52

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 53

Verdict: RUNTIME ERROR

Test 54

Verdict: WRONG ANSWER

Test 55

Verdict: RUNTIME ERROR

munmap_chunk(): invalid pointer

Test 56

Verdict: WRONG ANSWER

Test 57

Verdict: RUNTIME ERROR

Test 58

Verdict: RUNTIME ERROR

Test 59

Verdict: WRONG ANSWER

Test 60

Verdict: WRONG ANSWER

Test 61

Verdict: TIME LIMIT EXCEEDED

Test 62

Verdict: TIME LIMIT EXCEEDED

Test 63

Verdict: TIME LIMIT EXCEEDED

Test 64

Verdict: TIME LIMIT EXCEEDED

Test 65

Verdict: TIME LIMIT EXCEEDED