#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("grupuri.in");
ofstream g("grupuri.out");
int k,n,a[100001];
long long sum;
bool valid(int m)
{
    int i;
    long long s=0;
    for(i=1;i<=n;i++)
     s=s+min(a[i],m);
    if(s>=m*k)
      return true;
    return false;
}
int CB(int p,int q)
{
    int m,s;
    s=-1;
    while(p<=q)
    {
        m=(p+q)/2;
        if(valid(m))
        {
            s=m;
            p=m+1;
        }
        else
          q=m-1;
    }
    return s;
}
int main()
{
    int i,x;
    f>>k>>n;
    for(i=1;i<=n;i++)
    {
        f>>a[i];
        sum=sum+a[i];
    }
    sum=sum/k;
    x=CB(0,sum);
    g<<x;
    return 0;
}