View Code of Problem 18

#include <iostream>
using namespace std;
int main(){
	int n;
	while(cin>>n){
		int sum=0;	
		for(int i=1;i<=n/2-1;i++){
			sum+=i;
		}
		sum*=2;
		if(n%2==1){
			sum+=n/2;
		}	
		cout<<sum<<endl;
	} 
}