View Code of Problem 18

#include<string.h>
#include<stdio.h>
#include<stdlib.h>

int main(){
	int n;
	while((scanf("%d",&n)!=EOF)){
		int sum = 0,k=0;
		for(int i=1; i<=n; i++){
			sum = sum + k;
			if(i%2==0){
				k++;
			}
		
		}
		printf("%d\n",sum);
	}

}