#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

long double fact(ll n){
    long double t=1;
    for(int i=1;i<=n;i++)t*=i;
    return t;
}
int main(){
    long double t;cin >> t;
    CST(20);
    long double p=0;
    for(ll n=0;n<=10;n++){
        long double now=pow(-1,n);
        now*=fact(4*n);
        now*=(1123+21640*n);
        now/=pow(882,2*n+1);
        now/=pow(pow(4,n)*fact(n),4);
        p+=now;
        //cout << p <<endl;
    }
    long double q=sqrt(2);q*=2;q/=99*99;
    p/=q;
    long double r=0;
    for(int n=0;n<=10;n++){
        long double now=fact(4*n);
        now*=1103+26390*n;
        now/=pow(pow(396,n)*fact(n),4);
        r+=now;
        //cout << r <<endl;
    }
    //cout << t*p/r <<endl;
    cout << t*4 <<endl;
}