/// Coded by Dhiman Sarker Bappi (Dhimanda) - RMSTU

#include<bits/stdc++.h>
using namespace std;
#define    in_file     freopen("input.txt", "r", stdin)
#define    out_file    freopen("output.txt", "w", stdout)
#define    fast        ios_base :: sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define    F           first
#define    S           second
#define    pb          push_back
#define    popb        pop_back
#define    pf          push_front
#define    popf        pop_front
#define    lcm(a,b)    (a*b)/gcd(a,b)
#define    gcd(a,b)    __gcd(a,b)
#define    pi          2*acos(0)
#define    elif        else if
#define    ll          long long
#define    nl          '\n'
#define    endl        '\n'
#define    fori(i,b,e) for(int (i)=(b); (i) <= (e); (i)++)
#define    for0(i,n)   for(int (i)=0; (i) < (n); (i)++)

// ===================== DEBUG  ==========================

vector<string>vec_spltr(string s){s+=',';vector<string>res;while(!s.empty())
res.push_back(s.substr(0, s.find(','))),s=s.substr(s.find(',')+1);return res;}
void dbg_out(vector<string>__attribute__((unused))args,__attribute__((unused))int idx,
__attribute__((unused))int LINE_NUM){cerr<<endl;}template<typename Head,typename... Tail>
void dbg_out ( vector <string> args, int idx, int LINE_NUM, Head H, Tail... T)
{if(idx>0)cerr<<", ";else cerr << "Line(" << LINE_NUM << ") ";stringstream ss;ss<<H;
cerr<<args[idx]<<" = "<<ss.str();dbg_out(args,idx+1,LINE_NUM, T...);}
#define debug(...) dbg_out(vec_spltr(#__VA_ARGS__), 0, __LINE__, __VA_ARGS__)

// ===================== custom function ==========================

ll pow_mod(ll nn, ll pp, ll mm) { ll res = 1; while(pp > 0) { if(pp&1) res = (res * nn) % mm; pp = pp >> 1; nn = (nn * nn) % mm; } return res; }
class stdout_cus
{
    short float_prec = 7;
public:
    inline stdout_cus operator<<(const int& arg){ printf("%d",arg); return *this; }
    inline stdout_cus operator<<(const short& arg){ printf("%d",arg); return *this; }
    inline stdout_cus operator<<(const bool& arg){ printf("%d",arg); return *this; }
    inline stdout_cus operator<<(const unsigned int& arg){ printf("%u",arg); return *this; }
    inline stdout_cus operator<<(const unsigned short& arg){ printf("%u",arg); return *this; }
    inline stdout_cus operator<<(const long long& arg){ printf("%lld",arg); return *this; }
    inline stdout_cus operator<<(const unsigned long long& arg){ printf("%llu",arg); return *this; }
    inline stdout_cus operator<<(const double& arg){ printf("%.*f",float_prec,arg); return *this; }
    inline stdout_cus operator<<(const float& arg){ printf("%.*f",float_prec,arg); return *this; }
    inline stdout_cus operator<<(const char& arg){ printf("%c",arg); return *this; }
    inline stdout_cus operator<<(const unsigned char& arg){ printf("%c",arg); return *this; }
    inline stdout_cus operator<<(const char* arg){ printf("%s",arg); return *this; }
    inline stdout_cus operator<<(const std::string& arg){ printf("%s",arg.c_str()); return *this; }
    inline stdout_cus operator<<(const stdout_cus&){ return *this; }
    inline void ignore() { fflush(stdout); }
    inline stdout_cus precision(short prec) { float_prec = prec; return *this; }
}cout_cus;
class stdin_cus
{
public:
    inline stdin_cus operator>>(const int& arg){ scanf(" %d",&arg); return *this; }
    inline stdin_cus operator>>(const short& arg){ scanf(" %d",&arg); return *this; }
    inline stdin_cus operator>>(const bool& arg){ scanf(" %d",&arg); return *this; }
    inline stdin_cus operator>>(const unsigned int& arg){ scanf(" %u",&arg); return *this; }
    inline stdin_cus operator>>(const unsigned short& arg){ scanf(" %u",&arg); return *this; }
    inline stdin_cus operator>>(const long long& arg){ scanf(" %lld",&arg); return *this; }
    inline stdin_cus operator>>(const unsigned long long& arg){ scanf(" %llu",&arg); return *this; }
    inline stdin_cus operator>>(const double& arg){ scanf(" %lf",&arg); return *this; }
    inline stdin_cus operator>>(const float& arg){ scanf(" %f",&arg); return *this; }
    inline stdin_cus operator>>(const char& arg){ scanf(" %c",&arg); return *this; }
    inline stdin_cus operator>>(const unsigned char& arg){ scanf(" %c",&arg); return *this; }
    inline stdin_cus operator>>(const char* arg){ scanf(" %s",arg); return *this; }
    inline stdin_cus operator>>(std::string& arg){ char tmp[1000000]; scanf(" %s",tmp); arg = tmp; return *this; }
    inline void ignore() { fflush(stdin); }
}cin_cus;
#define    cout        cout_cus
#define    cin         cin_cus
#define    sp          cout_cus.precision
void dhimanda();
// ===================== Main function ==========================
int main()
{
    //in_file;
    //out_file;
    int t=1;
    //cin >> t;
    fori(i,1,t){
        //printf("Case %d: ", i);
        dhimanda();
    }
    return 0;
}
void dhimanda(){
    long long int a;
    double b;
    cin >> a;
    cin >> b;
    long long int bi = (long long int)(( b + 0.00001) * 100);
    cout << (a * bi / 100);
}

// Contact : chessdhiman@gmail.com


Measured memory_bytes: 3772