#include <stdio.h>
#include <stdlib.h>

int main(){
	unsigned long long a;
	double b;
	unsigned long long mult;
	
	if(scanf("%llu %lf",&a,&b) != 2){
		perror("scanf");
		exit(1);
	}
	mult = (unsigned long long)(a*b);
	printf("%llu",mult);
	return 0;
}