#include<bits/stdc++.h>
#define int unsigned long long
using namespace std;
int n,m,m1,a[1919810],x,y,z,mi=1111111;
signed main(){
scanf("%lld %lld %lld",&n,&m,&m1);
x=pow(m,m1);
for(int i=1;i<=n;++i){
scanf("%lld",&a[i]);
}
z=1;
for(int i=1;i<=n;++i){
z=1;
for(int j=1;j<10000;++j){
z=(z*a[i])%x;
if(z==0){
y=j;
if(y<mi){
mi=y;
break;
}
}
}
}
if(x==1) cout<<0;
else{
if(mi==1111111) cout<<-1;
else cout<<mi;
}
return 0;
}