#include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include <cmath>
using namespace std;
typedef long long ll;
int main(){
    ll a;
    long double b;
    ll c;
    ll d;
    ll tmp;
    cin>>a>>b;
    tmp=b*100;
    //cout<<tmp<<endl;
    c=tmp/100;
    //cout<<"c : "<<c<<endl;
    d=tmp-c*100;
    //cout<<"d : "<<d<<endl;
    
    ll x=a*c;
    ll y=a*d/100;
    //cout<<x<<endl;
    //cout<<y<<endl;
    cout<<x+y<<endl;


    return 0;
}