#include <bits/stdc++.h>
using namespace std;
// #define int long long
using ll=long long;
using vi=vector<int>;
using vl=vector<long long>;
using pii=pair<int,int>;
#define ITR(v,c) for(auto v=begin(c);v!=end(c);v++)
#define FOR(v,a,n) for(int v=a;v<(int)(n);v++)
#define FORE(x,arr) for(auto &x:arr)
#define REP(v,n) FOR(v,0,n)
#define RREP(v,n) for(int v=((int)(n)-1);v>=0;v--)
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)
#define SZ(c) ((int)c.size())
#define DUMP(x) cerr<<#x<<":="<<(x)<<endl
const int DX[9]={0,1,0,-1,1,1,-1,-1,0}, DY[9]={-1,0,1,0,-1,1,1,-1,0};
const int INF=1e9; const long long INFLL=1e18;
template<class T,class U>ostream&operator<<(ostream &os,const pair<T,U> &p){
    os<<"("<<p.first<<" "<<p.second<<")";return os;}
template<class T>ostream&operator<<(ostream &os,const vector<T> &v){
    ITR(i,v)os<<*i<<(i==end(v)-1?"":" ");return os;}
//------------------------------------------------------------------------------

signed main() {
    string d="0.1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
    int n;
    cin>>n;
    int kuriage=0;
    string ans;
    RREP(i,192) {
        if(i==1) break;
        int t=(d[i]-'0');
        t*=n;
        t+=kuriage;
        kuriage=t/10;
        t%=10;
        ans.push_back(t+'0');
    }
    reverse(ALL(ans));
    ans=to_string(kuriage)+"."+ans;
    cout<<ans<<endl;
    return 0;
}