#include<stdio.h>
#include<string.h>
#include<math.h>
#include<stdlib.h>
#include<ctype.h>

//qsort
int compare_int(const void *a, const void *b)
{
    return *(int*)a - *(int*)b;
}

//比較
int max(int a, int b){
	if (a>b) return a;
	else return b;
}

int min(int a,int b) {
	if(a>b) return b;
	else return a;
}


//main関数
int main() {
	long long A;
	float B;
	scanf("%lld %f",&A,&B);
	long long sakoda = B*100;
	long long answer = A*sakoda;
	printf("%lld",answer / 100);
	 
}