#include<stdio.h>
#include<string.h>

int main()
{
	long long int a = 0;
	double b = 0;
	long long int c, d;

	scanf("%lld %lf", &a, &b);

    d = (long long int)(b*100);

	c = a*d/100;

	printf("%lld", c);

	return 0;
}