486A - Calculating Function

#include <cmath>#include <cstdio>#include <cstdlib>#include <cstring>#include <iostream>#include <string>#include <vector>#include <queue>#include <algorithm>using namespace std;int main() {    long long n, ans;    cin >> n;    ans = n / 2;    if(n%2) ans -= n;    cout << ans << endl;    return 0;}