题解

#include <bits/stdc++.h>
using namespace std;
int main(){
    int a,b,c,d;
    cin >> a >> b >> c >> d;
    switch(a+b+c+d){
        case 0:
        cout << "0";
        break;
        case 1:
        cout << "1";
        break;
        case 2:
        cout << "2";
        break;
        case 3:
        cout << "1";
        break;
        case 4:
        cout << "0";
        break;
    }
    return 0;
}