#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin ("grupuri.in");
ofstream fout ("grupuri.out");
long long s,nr;
int maxc,n,i,k,v[100001];
int main()
{
    fin>>k>>n;
    for (i=1; i<=n; i++)
    {
        fin>>v[i];
        s=s+v[i];
        if (v[i]>maxc)
            maxc=v[i];
    }
    nr=s/k;
    if (1ll*n*16*maxc>5000000000)
        fout<<nr;
    else
    {
        nr=0;
        for (; ;)
        {
            for (i=n; i>=n-k+1; i--)
            {
                if (v[i]==0)
                {
                    fout<<nr;
                    return 0;
                }
                v[i]--;
            }
            nr++;
            sort (v+1,v+n+1);
        }
    }
    return 0;
}