题解 | #特殊乘法#

#include<iostream>
#include<cstdio>
#include<string>

using namespace std;

int main() {
	string str1;
	string str2;
	while(cin >> str1 >> str2) {
		int answer = 0;
		for(int i = 0; i < str1.size(); ++i) {
			for(int j = 0; j < str2.size(); ++j) {
				answer += (str1[i] - '0') * (str2[j] - '0');
			}
		}
		printf("%d\n",answer);
	}
	return 0;
}