View Code of Problem 18

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