#include <iostream>

using namespace std;

int main()
{
    int A;
    int B;
    int C;
    int a;
    cout<<"how much:";
    cin>>a;
    int b;
    cout<<"how much:";
    cin>>b;
    int c;
    cout<<"how much:";
    cin>>c;
    int n;
    cin>>n;
    int t;
    while(a !=0 &&b!=0&&c!=0){
        if(n%3==0){
            cout<<"ok";
        }
        t++;
    }
    bool are fine =true;
    if(n%!==0){
        are ok =false;;
    }
    if(a+A==b+B && b+B==c+C && a+A== c+C){
        cout<<"is also ok";
    }
    cout<<t;






    return 0;
}