//Grupuri - infoarena
#include <stdio.h>
#define INPUT "grupuri.in"
#define OUTPUT "grupuri.out"
#define MAXN 100001

int v[MAXN];
int N, K;
long long S;

int pos(int p)
{
	int i;
	long long nr;
	for(i = 1; i <= N; ++i)
		nr += v[i] % (p+1);
	if(nr / p >= K) return 1;
	return 0;
}
int main()
{
	freopen(INPUT, "r", stdin);
	scanf("%d %d", &K, &N);
	int i;
	for(i = 1; i <= N; ++i)
		scanf("%d", &v[i]),
		S += v[i];
		
	int st = 0, dr = S/K, mij;
	while(st < dr)
	{
		mij = (st + dr + 1)/2;
		if(pos(mij)) st = mij;
		else dr = mij -1;
	}
	
	freopen(OUTPUT, "w", stdout);
	printf("%d\n", mij);
	return 0;
}