#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,c,h;
    cin>>n;
    c=(n+1)/2;
    h=c*c;
    cout<<h<<endl;
    return 0;
}
/**************************************************************
	Problem: 1110
	User: HUANGYIBO
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/