#include <iostream>

using namespace std;

int main()
{
    int k;
    cin >> k;
    int t1;
    cin >> t1;
    int t2;
    cin >> t2;
    int t3;
    cin >> t3;
    int t4;
    cin >> t4;
    int t5;
    int zbir = t1 + t2 +t3 +t4;
    for(int i=0; i <= 100; i++) {
        int vkupno = zbir + i;
        vkupno /= 5;
        if(k == 2 and vkupno >= 60) {
            cout << i <<endl;
            return 0;
        }
        else if(k == 3 and vkupno >=70){
            cout << i <<endl;
            return 0;
        }
        else if(k== 4 and vkupno >= 80){
            cout<< i <<endl;
            return 0;
        }
        else if(k == 5 and vkupno >= 90){
            cout << i<<endl;
            return 0;
        }


    }
cout << "GRESHKA" <<endl;

    return 0;
}