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

class yc299
{
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NMap(int n) => Enumerable.Repeat<int>(0, n).Select(_ => NList).ToArray();
    static void Main()
    {
        var c = NList;
        var a = NList;
        var b = NList;
        var max = a.Length * b.Length / GCD(a.Length, b.Length);
        for (var i = 0; i < max; ++i)
        {
            if (a[i % a.Length] == b[i % b.Length])
            {
                WriteLine(i + 1);
                return;
            }
        }
        WriteLine(-1);
    }
    static int GCD(int a, int b)
    {
        if (a < b) return GCD(b, a);
        if (a % b == 0) return b;
        return GCD(b, a % b);
    }
}