#include<cstdio>
long long a[100001],n,i,k,s,st,dr,mij,x;
long long check(long long m)
{
	long long  x=m*k;
	for(i=1;i<=n && x>0;i++)
		if(a[i]>m) x-=m;
		else x-=a[i];
	return x<=0;
}
long long search(long long st,long long dr)
{
	if(st==dr) if(check(st)) return st; else return 0;
	long long mij=(st+dr)>>1;
	if(check(mij)){
		int k=search(mij+1,dr);
		if(k) return k;
		else return mij;}
	else
		return search(st,mij-1);		
}
int main()
{
	freopen("grupuri.in","r",stdin);
	freopen("grupuri.out","w",stdout);
	scanf("%lld %lld",&k,&n);
	for(i=1;i<=n;i++){
		scanf("%lld",&a[i]);
		s+=a[i];}
	printf("%lld\n",search(1,s/k));
	fclose(stdout);
	return 0;
}