View Code of Problem 18

#include<stdio.h>
int main(){
	int n;
	while(~scanf("%d", &n)){
		if(n == 1 || n == 2){
			printf("0\n");
		} else {
			int i, sum = 1, k = 1;
			for(i = 3; i < n; i ++){
				if(i % 2 == 0){
					k ++;
				}
				sum += k;
			}
			printf("%d\n", sum);
		}
	}
	return 0;
}