坑

要用long long
代码如下：

#include <bits/stdc++.h>
using namespace std;
int main() {
	string s;
    int m;
    cin >> m;
	cin >> s;
	int sum = 0;
	for (int i = s.size() - 1, j = 1; i >= 0; i--, j *= m) {
		sum += int(s[i] - '0') * j;
	}
    long long x = sum;//注意！
    //cout << x;
    sum = 0;
    cin >> s;
    for (int i = s.size() - 1, j = 1; i >= 0; i--, j *= m) {
		sum += int(s[i] - '0') * j;
	}
    long long y = sum;//注意！
    //cout << y;
    cout << x * y;
	return 0;
}