#include<bits/stdc++.h>
using namespace std;
int a[102]={0,3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6,4,3,3,8,3,2,7,9,5,0,2,8,8,4,1,9,7,1,6,9,3,9,9,3,7,5,1,0,5,8,2,0,9,7,4,9,4,4,5,9,2,3,0,7,8,1,6,4,0,6,2,8,6,2,0,8,9,9,8,6,2,8,0,3,4,8,2,5,3,4,2,1,1,7,0,6,8,0},n;
int main()
{
    cin>>n;
    if (a[n+1]>=5)
        a[n]+=1;
    for (int i=1;i<=n+1;i++)
    {
        cout<<a[i];
        if (i==1)
            cout<<".";
    }
    return 0;
}