C :

#include<stdio.h>
int main()
{
	int c;
	scanf("%d",&c);
	printf("%.2f",(c*1.0/4)*(c*1.0/4));
	return 0;
}

C++ :

#include <bits/stdc++.h>
using namespace std;

int main(){
	int n;
	cin>>n;
	cout<<fixed<<setprecision(2)<<n/4.0*n/4.0<<endl;
}

Python :

a=int(input())
b=a/4
print("%.2lf"%(b*b))