#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("grupuri.in");
ofstream fout("grupuri.out");
int main()
{
    int n,k,i,y;
    long long int s=0;
    fin>>k>>n;
    i=1;
    int x;
    for(int j=1;j<=n;j++)
    {
        y=x;
        fin>>x;
        s+=x;
    }
    i=s/k;
    if(x-i>=s%k && y-i>=s%k)
    {
        fout<<i-2;
    }
    else if(x-i>=s%k) fout<<i-2;
    else
    fout<<i;
    return 0;
}