using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var a0 = NList;
        var a1 = NList;
        a0[1] %= a0[0];
        a1[1] %= a1[0];
        if (a0[1] < 0) a0[1] += a0[0];
        if (a1[1] < 0) a1[1] += a1[0];
        for (var i = 0; i <= a0[0] * a1[0]; ++i)
        {
            if (i % a0[0] == a0[1] && i % a1[0] == a1[1])
            {
                WriteLine(i);
                return;
            }
        }
        WriteLine("NaN");
    }
}