《高精度乘法》

#include <bits/stdc++.h>

using namespace std;

vector<int> mul(vector<int> &A, int b)
{
    vector<int> C;
    int t = 0;
    
    for (int i = 0; i < A.size() || t; i ++)
    {
        if (i < A.size()) t += A[i] * b;
        C.push_back(t % 10);
        t /= 10;
    }
    
    while (C.size() > 1 && C.back() == 0) C.pop_back();
    
    return C;
}

int main()
{
    string a;
    int b;
    cin >> a >> b;
    
    vector<int> A;
    for (int i = a.size() - 1; i >= 0; i --) A.push_back(a[i] - '0');
    
    auto C = mul(A, b);
    
    for (int i = C.size() - 1; i >= 0; i --) cout << C[i];
    
    return 0;
}