#include <stdio.h>

int main(void)
{
	unsigned long a, b, c, d;
	unsigned long ans;

	scanf("%ld %ld %ld %ld", &a, &b, &c, &d);
	
	ans = a * b * c;
	ans %= d;

	printf("%ld\n", ans);

	return 0;
}