#include <cstdio>
#include <iostream>
#define N 1000001
#define LL long long
#define max(x, y) ((x) > (y) ? (x) : (y))
#define min(x, y) ((x) < (y) ? (x) : (y))

int n, m1, m2, m, sum, ans = 1e9, tot, t = 1, p;
int b[N], c[N];
bool f;

inline int read()
{
    int x = 0, f = 1;
    char ch = getchar();
    for(; !isdigit(ch); ch = getchar()) if(ch == ‘-‘) f = -1;
    for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - ‘0‘;
    return x * f;
}

inline int gcd(int x, int y)
{
    return !y ? x : gcd(y, x % y);
}

int main()
{
    int i, j, a, x;
    n = read();
    m1 = read();
    m2 = read();
    if(m1 == 1)
    {
    	puts("0");
    	return 0;
    }
    x = m1;
    for(j = 2; j <= m1; j++)
    {
	    while(!(x % j)) c[t] = j, b[t]++, x /= j;
        b[t] *= m2;
		if(b[t]) t++;
	}
	t--;
    for(i = 1; i <= n; i++)
    {
        sum = f = 0;
        p = 1;
        x = a = read();
        if(gcd(m1, a) == 1) continue;
        for(j = 2; j <= a; j++)
        {
            tot = 0;
            while(!(x % j)) tot++, x /= j;
            if(tot && c[p] == j) sum = max(sum, b[p] / tot + (b[p] % tot != 0)), p++;
            if(c[p] < j) break;
        }
        if(p > t) ans = min(ans, sum);
    }
    printf("%d\n", ans == 1e9 ? -1 : ans);
    return 0;
}