#include<stdio.h>
long a,n,m,i,t;
long long s=0;
int main()
{freopen("grupuri.in","r",stdin);
freopen("grupuri.out","w",stdout);
scanf("%ld%ld",&n,&m);
for(i=1;i<=m;i++)
       scanf("%ld",&a),s+=a,t=a;
if(s/n>=t)
       printf("%lld",s/n);
else
       printf("%lld",(s-t)/n+1);
return 0;}