a times b

input/code.cpp: In function 'std::string multiply(std::string, std::string)':
input/code.cpp:11:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |     for (int i = 0; i < num1.size(); i++) {
      |                     ~~^~~~~~~~~~~~~
input/code.cpp:15:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |     for (int i = 0; i < num2.size(); i++) {
      |                     ~~^~~~~~~~~~~~~
input/code.cpp:23:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   23 |     for (int i = 0; i < vec2.size(); i++) {
      |                     ~~^~~~~~~~~~~~~
input/code.cpp:25:27: warning: comparison o...

#include <iostream>
#include <vector>
#include <string>
#define int long long

using namespace std;

string multiply(string num1, string num2) {
    // Convert the input numbers from strings to vectors of integers
    vector<int> vec1(num1.size());
    for (int i = 0; i < num1.size(); i++) {
        vec1[i] = num1[num1.size() - i - 1] - '0';
    }
    vector<int> vec2(num2.size());
    for (int i = 0; i < num2.size(); i++) {
        vec2[i] = num2[num2.size() - i - 1] - '0';
    }

    // Initialize the result vector with zeros
    vector<int> result(vec1.size() + vec2.size());

    // Multiply each digit in vec2 with vec1 and add the result to the appropriate position in the result vector
    for (int i = 0; i < vec2.size(); i++) {
        int carry = 0;
        for (int j = 0; j < vec1.size(); j++) {
            int product = vec1[j] * vec2[i] + carry + result[i + j];
            carry = product / 10;
            result[i + j] = product % 10;
        }
        result[i + vec1.size()] = carry;
    }

    // Remove leading zeros from the result vector and convert it back to a string
    while (result.size() > 1 && result.back() == 0) {
        result.pop_back();
    }
    string str(result.size(), '0');
    for (int i = 0; i < result.size(); i++) {
        str[result.size() - i - 1] = result[i] + '0';
    }
    return str;
}

int main() {
    string a,b;
    cin >> a >> b;
    cout << multiply(a, b) << endl;

    return 0;
}