View Code of Problem 18

#include<stdio.h>
int main()
{
	int a[10010];
	a[3]=1;a[4]=2;
	for(int i=4;i<10010;++i){
		a[i]=a[i-1]+(i+1)/2-1;
	}
	int n;
	while(scanf("%d",&n)!=EOF){
		printf("%d\n",a[n]);
	}
	return 0;
}