// Slower C++ solution:
/***

 **   A S M Atikur Rahman

 **   Updated: 08-06-2020

***/



//#include <bits/stdc++.h>

#include<iostream>

#include<stdio.h>

#include<stdlib.h>

#include<math.h>

#include<cstring>

#include<cctype>

#include<time.h>

#include<climits>

#include<vector>

#include<string>

#include<stack>

#include<queue>

#include<map>

#include<unordered_map>

#include<set>

#include<unordered_set>

#include<bitset>

#include<utility>

#include<iterator>

#include<algorithm>

#include<cassert>

#include<iomanip> ///setprecision





#define fastIO ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);

#define Filein(N) freopen("N", "r", stdin);

#define Fileout(N) freopen("N", "w", stdout);

#define sci(x) scanf("%d%*c", &(x))

#define sci2(x,y) scanf("%d%*c%d%*c", &(x), &(y))

#define sci3(x,y,z) scanf("%d%*c%d%*c%d%*c", &(x), &(y), &(z))

#define scll(x) scanf("%lld%*c", &(x))

#define scll2(x,y) scanf("%lld%*c%lld%*c", &(x), &(y))

#define scll3(x,y,z) scanf("%lld%*c%lld%*c%lld%*c", &(x), &(y), &(z))

#define scd(x) scanf("%lf%*c", &(x))

#define scd2(x,y) scanf("%lf%*c%lf%*c", &(x), &(y))

#define scstr(x) scanf("%s", x)

#define pfi(x) printf("%d", (x))

#define pfi2(x,y) printf("%d %d", (x), (y))

#define pfll(x) printf("%lld", (x))

#define pfll2(x,y) printf("%lld %lld", (x), (y))

#define pfd(x) printf("%f", (x))

#define pfstr(x) printf("%s", (x))

#define ps printf(" ")

#define pn printf("\n")

#define pfdot printf("..")



#define For(i,a,n) for(int i=(a); i<=(n); i++)

#define rFor(i,n,a) for(int i=n; i>=a; i--)

#define trav(a,x) for (auto &a : x)

#define Ms(ara, val) memset(ara, val, sizeof(ara))

#define TestCase int testcase, cs=1; cin>>testcase;while(testcase--)



#define All(V) V.begin(), V.end()

#define rAll(V) V.rbegin(), V.rend()



#define mkp make_pair

#define pb push_back

#define ff first

#define ss second

#define lb lower_bound

#define ub upper_bound



#define Ceil(a,b) ((a/b)+((a%b)!=0))

#define Sq(a) ((a)*(a))



#define P(x) cout<<"Check X: "<<x;

#define P2(x,y) cout<<"Check X,Y: "<<x<<" "<<y;

#define P3(x,y,z) cout<<"Check X,Y,Z: "<<x<<" "<<y<<" "<<z;



using namespace std;



using ll=long long;

using pii= pair<int,int>;

using pll= pair<long long, long long>;

using pcc= pair<char, char>;

using pdd= pair<double, double>;



#define V(a) vector<a>

using vi= vector<int>;

using vs= vector<string>;

using vll= vector<ll>;

using vpii= vector<pii>;

using vc= vector<char>;

using vd= vector<double>;





/*------------------------Bitmask--------------------------*/



//INTEGER

#define Toggle(n,i) (n^(1<<i))

#define Check(n,i) (n&(1<<i))

#define Set(n,i) (n|(1<<i))

#define Reset(n,i) (n&(~(1<<i)))



////LONG LONG INTEGER

//#define Toggle(n,i) (n^((1ll)<<i))

//#define Check(n,i) (n&((1ll)<<i))

//#define Set(n,i) (n|((1ll)<<i))

//#define Reset(n,i) (n&(~((1ll)<<i)))



//// Functions for Bitmask

//template <typename T> inline T Set(T &n, T p){T on=1;return n= n|(on<<p);}

//template <typename T> inline T Reset(T &n, T p){T on=1;return n= n&(~(on<<p));}

//template <typename T> inline bool Check(T n, T p){T on=1;return (bool) (n&(on<<p));}

//template <typename T> inline T Toggle(T &n, T p){T on=1;return n= n^(on<<p);}





/*----------------------------------------------------------*/



/*------------------------Graph_Moves-------------------------*/



//const int fx[]={+1,-1,+0,+0};

//const int fy[]={+0,+0,+1,-1};



/*------------------------------------------------------------*/





/*------------------------Declarations------------------------*/



//priority_queue<int,vector<int>, greater<int>>  //priority queue sorted in increasing order



/*------------------------------------------------------------*/





template <typename T> T POW(T a, T b){ T x=1;while(b){ if(b&1)x*=a;a*=a;b>>=1; }return x; }

template <typename T> T mPOW(T a, T b, T M){ T x=1;while(b){ if(b&1) x=(x*a)%M;a=(a*a)%M;b>>=1; }return x; }

template <typename T> T Sqrt(T a) { T x=(T)sqrt(a); if((x+1)*(x+1)==a) x++; return x; }





#define INF 1000000000

#define LINF 4000000000000000000

#define pi  (2*acos(0))

#define Mod 1000000007











int main( int argc, char *argv[] )

{



    ll a,b;

    double c;

    scll(a),scd(c);

    b=(ll)round(c*100);

    pfll((a*b)/100),pn;



    return 0;

}




































































































// Faster C++ solution for the same problem (measured speedup: 5.099818606192506x):
#include <stdio.h>

#include <string.h>

int main()

{

	int i,j,k,t,n,m,l,x,y,z;

	double b;

	long long a,c,d;

    while(scanf("%lld%lf",&a,&b)!=EOF){

    	d=b*100+0.1;

    	c=a*d/100;

    	printf("%lld\n",c);

	}

    return 0;

}