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;
}