Codeforces Round #251 (Div. 2) A - Devu, the Singer and Churu, the Joker

水题

#include <iostream>

#include <vector>

#include <algorithm>

using namespace std;
int main(){

    int n,d,t;

    cin >> n >> d;

    for(int i = 0 ; i < n; ++ i){

        cin >> t;

        d-=t;

    }

    d-=(n-1)*10;

    if(d < 0) cout<<-1<<endl;

    else cout<<(n-1)*2+d/5<<endl;

}

Codeforces Round #251 (Div. 2) A - Devu, the Singer and Churu,
the Joker