407 - 1 + 2 + 3 + . . . + n = k

1 + 2 + 3 + . . . + n = k

Time Limit: 1 sec

**The Problem**

Given the following formula, in order to obtain a given **k**, you need to find the value of **n**.

1 + 2 + 3 + ... + **n** = **k**

For example:

Given **k** = 15, the expression to be used will be

1 + 2 + 3 + 4 + 5 = 15 Here, **n** = 5

**The Input**

**Input file contain a series of line, each line contain one integers k (0< =k <=1000405). **Input is terminated by

**EOF**.

**The Output**

For each line of input, your program should print the minimal possible **n** (1<=n) to obtain k with the above formula.

**Sample Input**

15

5050

6

**Sample Output**

5

100

3

Problem Setter: Shahin ShamS