C :

#include <stdio.h>

 

void main(){

    int n;

    scanf("%d",&n);

    printf("%.1f%%",(2*n-1+4) * 100.0 / (n * n));

}

C++ :

#include<bits/stdc++.h>
using namespace std;
int main(){
int n;
cin>>n;
int zonggong =n*n;
int fense = 2*n+3;
double r = (double)fense / zonggong * 100;
cout<<fixed<<setprecision(1)<<r<<"%";
return 0;
}

Python :

n=int(input())
s=(2*n+3)/(n*n)*100
print('{:.1f}%'.format(s))