#include<bits/stdc++.h>
#include <cmath>
#define int long long
using namespace std;
int n,m=0x3f3f3f3f,m1,m2,a[10005];
int cell_division(int num,int x,int y,int time)
{
    if(x%y==0)
    {
        return time;
    }
    cell_division(num*x,x,y,time+1);
}
signed main()
{
    cin>>n;
    cin>>m1>>m2;
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
    }
    int sofa=pow(m1,m2);
    if(sofa%2==1)
    {
        int c=0;
        for(int i=0;i<n;i++)
        {
            if(a[i]%2==1)
            {
                c=1;
                break;
            }
        }
        if(c==0)
        {
            cout<<"-1";
            return 0;
        }
    }
    for(int i=0;i<n;i++)
    {
        m=min(cell_division(n,a[i],sofa,0),m);
    }
    cout<<m;
    return 0;
}