#include <iostream>
using namespace std;
int main(void){
    int n,c;
    cin >> n >> c;
    
    int cake=0;
    int p;
    for(int i=0;i<c;i++){
        cin >> p;
        cake += p;
    }
    if(cake%(n+1)==0) cout << cake/(n+1) << endl;
    if(cake%(n+1)!=0) cout << cake/(n+1)+1 << endl;
    return 0;
}

