#include<fstream.h>
#define N 100001
long long s,a[N],n,m,i;
int main()
{ifstream f("grupuri.in");
ofstream g("grupuri.out");
f>>n>>m;
for(i=1;i<=m;i++)
       f>>a[i],s+=a[i];
for(i=m;i;i--)
       {if(s/n>=a[i])
              {g<<(long long)(s/n);
              return 0;}
       s-=a[i];}
g<<"0";
return 0;}