牛牛学数列
牛牛学数列
https://ac.nowcoder.com/acm/problem/22156
#include<iostream>
using namespace std;
int main()
{
int n;
int sum = 0;
cin >> n;
for (int i = 1; i <= n; i++)
{
if (i % 2 == 0)
sum -= i;
else
sum += i;
}
cout << sum << endl;
return 0;
}
