#include <stdio.h>

int main(void) {
	unsigned long long a = 0;
	double b = 0;
	unsigned long long c = 0;
	int aa = 0;

	scanf("%llu", &a);
	scanf("%lf", &b);
	aa = b * 100;

	c = (aa * a) / 100;

	printf("%llu", c);

	return 0;
}