#include<bits/stdc++.h>
using namespace std;
void mul(vector<int> &a,int b){//高精度乘以低精度
    int t=0;
    for(int i=0;i<a.size();i++){
        t+=a[i]*b;
        a[i]=t%10;//用数组模拟这里是a[i]+=t%10;
        t=t/10;
    }
    while(t){
        a.push_back(t%10);
        t/=10;
    }
}
void sum(vector<int> &a,int k,int b){
    int t=b;
    for(int i=k;i<a.size();i++){
        t+=a[i];
        a[i]=t%10;
        t=t/10;
    }
    while(t){
        a.push_back(t%10);
        t/=10;
    }
}
int main(){
    int n;
    string s;
    cin>>n>>s;
    vector<int> a;
    reverse(s.begin(),s.end());
    for(auto x:s){
        if(x!='.')a.push_back(x-'0');
    }
   // for(auto x:a)cout<<x;
     int x=s.find('.');
     while(n--)mul(a,2);
     int k=x-1;
     if(a[x-1]>=5)sum(a,x,1);//x-1是小数点后一位，x是小数点前一位
     for(int i=a.size()-1;i>=x;i--)cout<<a[i];
    return 0;
}