#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    string s = "1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
    int a[200] = {};
    srep(i,10,200) a[i] = s[i-10] - '0';
    int n; cin >> n;
    int b[200] = {};
    drep(i,200){
        b[i] += a[i] * n;
        while(b[i] >= 10){
            b[i-1]++;
            b[i] -= 10;
        }
    }
    int mode = 0;
    rep(i,200){
        if(b[i] > 0 || i == 9) mode = 1;
        if(mode) cout << b[i];
        if(i == 9) cout << '.';
    }
    cout << endl;
    return 0;
}