486A Calculating-Function.cpp

#include<bits/stdc++.h>

using namespace std;


int main(){
    long long int n;
    cin >> n;
    if(n%2==0)
    {
        cout << n/2;
    }
    else
    {
        cout << ((n/2) + 1)*-1;
    }
    return 0;
}