import java.util.*;
import java.lang.*;
import java.io.*;
 
class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		float k = in.nextInt(), n = in.nextInt(), m = in.nextInt(), d = in.nextInt(), s = (d * k * n * m) / (k * n * m - k * m - k * n - m * n);
		if ((1 / k + 1 / n + 1 / m >= 1) | (Math.floor(s / k) != s / k | Math.floor(s / n) != s / n | Math.floor(s / m) != s / m) | !(Math.floor(s) == s))
			System.out.println(-1);
		else System.out.println(Math.round(s));
	}
}

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3	2	5	8