#include<fstream>
using namespace std;
ifstream fin("grupuri.in");
ofstream fout("grupuri.out");
long long  k,n,i,v[100001],y,st,dr,s,ss,x;


int main()
{
    fin>>k>>n;
    for(i=1;i<=n;i++)
    {
        fin>>v[i];
        s+=v[i];
    }
    st=1;
    dr=s/k;
    while(st<=dr)
    {
        ss=0;
        x=(st+dr)/2;
        for(i=1;i<=n;i++)
        {
            y=v[i];
            if(v[i]>=x)
                y=x;
            ss+=y;
        }
        if(ss-x*k<=x-1&&ss-x*k>=0)
            st=x+1;
        else
            if(ss-x*k>=x)
                st=x+1;
            else
                if(ss-x*k<=0)
                    dr=x-1;
    }
    fout<<dr;
    fin.close();
    fout.close();
    return 0;
}