#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	int a=n+n+3,b=n*n;
	float c=1.0*a/b*100;
	printf("%.1f%%",c);
	return 0;
}
/**************************************************************
	Problem: 1345
	User: fuhoubin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/