#include <iostream>
#include <fstream>


using namespace std;
ifstream fin("loto.in");
ofstream fout("loto.out");

int n,ok,i;
long s,v[100],a[6],j,aux,p;
int main()
{fin>>n>>s;
for(i=i;i<=n;i++)
    fin>>v[i];
while(ok==0)
    {ok=1;
    for(i=1;i<n;i++)
        if(v[i]>v[i+1])
    {aux=v[i];
    v[i]=v[i+1];
    v[i+1]=aux;
    ok=1;}
    }
for(i=1;i<=6;i++)
    a[i]=v[1];
p=v[1]*6;
if(p>s)
    fout<<-1;
if(v[n]*6<s)
    fout<<-1;

    return 0;
}