#include <cstdio>
 
using namespace std;
 
FILE *fin = freopen("grupuri.in", "r",stdin);
FILE *fout = freopen("grupuri.out","w",stdout);
 
static const int NMAX = 1e5+5;
 
int n,k;
int v[NMAX];
long long int sumTotal;
long long int logN, pas;
int main()
{
    scanf("%d%d",&k,&n);
 
    for(int i= 1; i<= n; ++i)
    {
        scanf("%d",&v[i]);
        sumTotal+=v[i];
    }
    for(logN = 1; logN <= k*v[n]; logN<<=1);
 
    for(;logN; logN >>=1)
    {
        if((pas+logN)*k <= sumTotal)
            pas+=logN;
    }
 
    printf("%lld", pas);
    return 0;
}