View Code of Problem 18

#include<stdio.h>
#include<math.h>
int main()
{
	int n;
	int i;
	int a[10000];
	a[0]=0;a[1]=0;a[2]=1;
	for(i=3;i<10000;i++)
		a[i]=a[i-1]+i-1;
	while(scanf("%d",&n)!=EOF)
	{
	    int sum;
		sum=a[(n+1)/2]+a[n-(n+1)/2];
		printf("%d\n",sum);
	}
	return 0;
}