#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;

}