View Code of Problem 18

#include<stdio.h>
int main(){
	int n,sum1,sum2;
	while(scanf("%d",&n)!=EOF){
		if(n%2==0){
			sum1=(1+n/2-1)*(n/2-1)/2;
			printf("%d\n",sum1*2);
		}else{
			sum1=(1+n/2)*(n/2)/2;
			sum2=(1+n/2-1)*(n/2-1)/2;
			printf("%d\n",sum1+sum2);
		}
	}
	return 0;
}