#include <iostream>
#include <cmath>
#include <iomanip>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <string>
#include <cstring>
#include <set>
#include <map>
#include <ctime>
#include <cstdlib>

using namespace std;

const int N = 210000;

int i;
double x, y, z, a, b, c, d;

int main()
{
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    cin >> a >> b >> c >> d;
    for (i = 1; i < 10000001; i ++)
    {
                {
                    x = i / a;
                    y = i / b;
                    z = i / c;
                    if (x + y + z + d == i)
                        return cout << i, 0;
                }
    }
    cout << - 1;
    return 0;
}