View Code of Problem 18

#include<stdio.h>

int main()
{
	int n;
	int num[10000]={0};
	
	num[0] = 0;
	num[1] = 0;
	num[2] = 0;
	num[3] = 1;
	num[4] = 2;
	int x = 2;
	
	for(int i = 5; i < 10000; i++)
	{
		num[i] = num[i-1] + x;
		if(i % 2 == 0)
			x++;
	}
		
	while(scanf("%d", &n) != EOF)
		printf("%d\n", num[n]);
		
	return 0;
}