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

int main(){
  
  unsigned long long		A, ans, M;
  long double	B, N, k;
  
  scanf("%llu %Lf", &A, &B);
  k = B*100;
  ans = A*k/100;
  printf("%llu", ans);
  
  return 0;
}
