#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define ALL(x) (x).begin(), (x).end()
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
typedef vector<vector<int>> Matrix;


int main(){
  ll a;
  double b;
  cin >> a >> b;
  ll c = b * 100;
  ll ans = a * c;
  ans /= 100;
  cout << ans << endl;
}

