import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
//入力文字をの読み取り
    	Scanner sc = new Scanner(System.in);
        //1文字目
        long a = sc.nextInt();
        //2文字目
        long b = sc.nextInt();
      //3文字目
        long c = sc.nextInt();
      //4文字目
        long d = sc.nextInt();

        //計算
        long result = a*b;
        result = result*c;
        result = result%d;
        //出力
        	System.out.println(result);

    }
}