/*
 *   Copyright (c) 2025 Emon Thakur
 *   All rights reserved.
 */
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
//#define file cout

ll a[200005],pfs[31][200005],n,x;
bool notprime[100006];
vector<ll>allprime;
void seive()
{
    for(int i=2;i<=1000;i++)
    {
        if(notprime[i]) continue;
        for(int j=i+i;j<=100000;j+=i) notprime[j]=true;
    }
    for(int i=2;i<=100000;i++) {if(!notprime[i]) allprime.push_back(i);}
}

void calcpfs()
{
    for(ll k=x;k<x+30;k++)
    {
        vector<ll> pd;
        ll kk = k;
        for(auto p:allprime)
        {
            if(kk%p==0) pd.push_back(p);
            while(kk%p==0) kk/=p;
        }if(kk>1) pd.push_back(kk);

        for(int i=1;i<=n;i++)
        {
            ll cnt = k;
            for(auto gcd:pd)
            {
                if(a[i]%gcd==0) {cnt=0; break;}
                cnt = min(cnt ,((a[i]+gcd)/gcd)*gcd - a[i]);
            }
            pfs[k-x][i]  = pfs[k-x][i-1] + max(0ll,cnt);
        }
    }
}

ll ans(int start,int end,ll k)
{
    if(start==end){
        return pfs[k-x][start]-pfs[k-x][start-1];
    }
    int mid = (start+end-1)/2;
    ll costleft = pfs[k-x][mid]-pfs[k-x][start-1];
    ll costright = pfs[k-x][end]-pfs[k-x][mid];
    return min(costright + ans(start,mid,k+1) , costleft + ans(mid+1,end,k+1));
}

void solve(int tc)
{
    // string outp = "output"+to_string(tc)+".txt";
    // string inp = "input"+to_string(tc)+".txt";
    // ofstream file(outp);
    // freopen(inp.c_str(),"r",stdin);

    seive();
    cin >> n >> x;
    for(int i=1;i<=n;i++) cin >> a[i];
    if(x==1)
    {
        cout<<-1<<'\n';
        return;
    }
    calcpfs();
    cout << ans(1,n,x)<<'\n';
}


int main()
{
    solve(0);
    // int l=0,r=99;
    // for(int i=l;i<=r;i++) solve(i);
}