#include <iostream>
#include <vector>
#include <map>
#include <string>
#include <tuple>
#include <algorithm>
#include <cmath>
using namespace std;


int main(){
    long A;
    double B;
    cin >> A >> B;

    if((long)floor(A)==0 || (long)floor(B)==0){
        cout << 0 << endl;
        return 0;
    }

    double res = floor(A*B);
    long hoge = res;

    printf("%ld\n",hoge);
    
    return 0;
}
