#include<stdio.h>

int main(void)
{
	int N;
	 long long int sum;
	long long int A;
	double b;
	scanf("%lld", &sum);
	scanf("%lf",&b);
	A = b * 100;
	sum *= A;
	sum /= 100;
	

	
	printf("%lld",sum);

	return 0;
}