import java.io.*;
import java.util.*;
import java.util.stream.*;

class Process {
    private int A;
    private int B;
    private int C;
    private int D;

    Process(int A, int B, int C, int D) {
        this.A = A;
        this.B = B;
        this.C = C;
        this.D = D;
    }

    long getResult() {
        return (((((long)A * B) % D) * C) % D);
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        var bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        var printWriter    = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));

        // 入力
        int[] input = Stream.of(bufferedReader.readLine().trim().split("[ ]+")).mapToInt(Integer::parseInt).toArray();

        // 処理および出力
        printWriter.println((new Process(input[0], input[1], input[2], input[3])).getResult());
        
        bufferedReader.close();
        printWriter.close();
    }
}