package main

import (
	"bufio"
	"fmt"
	"io"
	"os"
)

func solve(in io.Reader, out, err io.Writer) {
	var a, b, c, d int64
	fmt.Fscan(in, &a, &b, &c, &d)
	answer := a
	answer = (answer * b) % d
	answer = (answer * c) % d
	fmt.Fprintln(out, answer)
}

func main() {
	br := bufio.NewReaderSize(os.Stdin, int(1e3))
	solve(br, os.Stdout, os.Stderr)
}