#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,c,s;
    cin>>n;
    c=(n+1)/2;
    s=c*c;
    cout<<s<<endl;
    return 0;
}
/**************************************************************
	Problem: 1003
	User: 12345678
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/