#include <iostream>
using namespace std;
int main(){
  int n, i = 0;
  cin >> n;
  while (n != 1){
    if (n <= 1){
        i+= n;
        n++;
    }
    else if (n >= 1){
        i+= n;
        n--;
    }
  }
    cout << i+1;
    return 0;
}

So what?

http://acm.timus.ru/status.aspx?space=1&num=1068&status=accepted&count=100

Edited by author 04.04.2017 11:39