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

#define rep(i,k,n) for(int (i)=(k);(i)<(n);(i)++)
#define max(a,b) (a)>(b)?(a):(b)
#define min(a,b) (a)<(b)?(a):(b)
#define abs(a) (a)>0 ?(a):-(a)
#define llong long long

int main(){
	llong A; scanf("%lld",&A);
	double B; scanf("%lf",&B);
	printf("%lld",(llong)(A*(B*100))/100);
	return 0;
}
