#include <bits/stdc++.h>
using namespace std;
int main() {
    char a[1001], b[1001];
    int target;
    cin >> a >> b >> target;
    int la = strlen(a), lb = strlen(b);
    int a1[1001] = {0}, b1[1001] = {0};
    for (int i = 0; i < la; i++) {
        a1[la - 1 - i] = a[i] - '0';
    }
    for (int i = 0; i < lb; i++) {
        b1[lb - 1 - i] = b[i] - '0';
    }
    int c1[2001] = {0};
    int x = 0;
    for (int i = 0; i < lb; i++) {
        x = 0;
        for (int j = 0; j < la; j++) {
            int sum = a1[j] * b1[i] + c1[i + j] + x;
            c1[i + j] = sum % 10;
            x = sum / 10;
        }
        c1[i + la] = x;
    }
    int lc = la + lb;
    while (lc > 0 && c1[lc - 1] == 0) lc--;
    if (lc == 0) lc = 1; 
    int cnt = 0;
    for (int i = 0; i < lc; i++) {
        if (c1[i] == target) cnt++;
    }
    cout << cnt << endl;

    return 0;
}

作弊方法：

#include<bits/stdc++.h>
using namespace std;
int main()
{
    cout<<3;
}