高精度 * 高精度 模板

#include <bits/stdc++.h>
using namespace std;

string mul(vector<int>& a, vector<int>& b) {
    vector<int> c(a.size() + b.size(), 0);
    for (int i = 0; i < a.size(); ++i) {
        for (int j = 0; j < b.size(); ++j) {
            c[i + j] += a[i] * b[j];
        }
    }
    for (int i = 0, t = 0; i < c.size(); ++i) {
        t += c[i];
        c[i] = t % 10;
        t /= 10;
    }
    while (c.size() > 1 && c.back() == 0) c.pop_back();
    string ans;
    for (int i = c.size() - 1; i >= 0; --i) ans += c[i] + '0';
    return ans;
}



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