#define A (x+y+1)*2<=d
#include <stdio.h>

int main(void)
{
	int d,t,x,y;
	scanf("%d",&d);
	x=d/4;
	y=d/4;
	while(1){
		if(A)x++;
		else break;
		if(A)y++;
		else break;
	}
	printf("%d",x*y);
	return 0;
}