#include<bits/stdc++.h>
using namespace std;
int main(){
  
    float ms,zs,b;
    int n ;
    
    cin>>n;
    zs=n*n;
    ms=n+n-1+4;
    b=ms*1.0/zs*100.0;
    printf("%.1f",b);
    cout<<'%'; 
    return 0;
}
/**************************************************************
	Problem: 1345
	User: zhangyilei
	Language: C
	Result: Compile Error
****************************************************************/