Problem Statement

Given a number $N$, find the minimum value of $K$ such that $\displaystyle N \leq \sum_{i=1}^{K}i$.

Constraints

• $1 \leq N \leq 10^{18}$.

Input

The input is given from Standard Input in the following format:

$\color{#cccccc}\boxed{\color{white}{\large{|}}\color{black}N\color{white}{\large{|}}}$

Output

Output the minimum value of $K$.

Sample Input 1

55

Sample Output 1

10

Sample Input 2

1000000000

Sample Output 2

44721