#include <fstream>
using namespace std;

ifstream is("grupuri.in");
ofstream os("grupuri.out");

#define ll long long

ll K, N, x[100001];
ll Sum;

bool Try(int cnt);
int BS();

int main()
{
    is >> K >> N;

    for ( int i = 1; i <= N; ++i )
        is >> x[i], Sum += x[i];

    os << BS();

    is.close();
    os.close();
    return 0;
}

bool Try(int cnt)
{
    ll S = 0;
    for ( int i = 1; i <= N; ++i )
    {
        if ( x[i] > cnt )
            S += cnt;
        else
            S += x[i];
        if ( S >= cnt * K )
            return true;
    }
    return false;
}

int BS()
{
    int i,step;
    for ( step = 1; step <= Sum/K; step <<= 1 );
    for ( i = 0; step; step >>= 1 )
    {
        if ( i + step <= Sum/K && Try(i + step) == true )
            i += step;
    }
    return i;
}