View Code of Problem 18

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

int main()
{
	int n;
	int a[1000]={0,0,1};

	while(~scanf("%d",&n)){
		int i,sum=0;
		for(i=3;i<n;i++)
			a[i]=a[i-1]+(i-1);
		sum=a[(n+1)/2]+a[n-(n+1)/2];
		printf("%d\n",sum );
	}



	return 0;
}