#include <stdio.h>

int main(void) {
	unsigned long long int a,b,c,d,r;
	scanf("%llu%llu%llu%llu",&a,&b,&c,&d);
	r = (a%d)*(b%d);
	r*=(c%d);
	printf("%llu\n",r);
	return 0;
}