View Code of Problem 18

#include <stdio.h>
#include <iostream>
#include <string.h>
#include <string>
#include <algorithm>
using namespace std;
int main()
{
	int i, n, k = 0, a[9999] = { 0 };
	for (int i = 1; i < 10000; i++) {
		a[i] = a[i - 1] + k;
		if (i % 2 == 0) {
			k++;
		}
	}
	while (cin >> n) {
		cout << a[n] << endl;
	}
}