Crne

#include <iostream>

using namespace std;

int main(){

    int n, a, b;
    cin >> n;
    a = n/2;
    b = a;
    if(n&1) b++;

    cout << a*b+a+b+1;

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED