using System;
using System.Collections.Generic;
using System.Linq;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] x = Console.ReadLine().Split().Select(int.Parse).ToArray();
            long ret = x[0] * x[1];
            ret %= x[3];
            ret *= x[2];
            ret %= x[3];
            Console.WriteLine(ret);
        }
    }
}