#include "bits/stdc++.h"
using namespace std;
#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
int n, k;
string s;

int main(){
	int D=0;
	cin>>D;
	if(D<4){cout<<0<<endl;return 0;}
	if(D%4==0){
		cout<<(D/4)*(D/4)<<endl;
	}else if(D%4==2){
		cout<<(D/4)*(D/4+1)<<endl;
	}else if(D%4==1){
		cout<<(D/4)*(D/4)<<endl;
	}else if(D%4==3){
		cout<<(D/4)*(D/4+1)<<endl;
	}
}