# Task
 You are given an array of integers `arr` that representing coordinates of obstacles situated on a straight line.
 Assume that you are jumping from the point with coordinate 0 to the right. You are allowed only to make jumps of the same length represented by some integer.
 Find the minimal length of the jump enough to avoid all the obstacles.
# Example
 For `arr = [5, 3, 6, 7, 9]`, the output should be `4`.
 Check out the image below for better understanding:
# Input/Output
 - `[input]` integer array `arr`
    Non-empty array of positive integers.
    Constraints: `1 ≤ inputArray[i] ≤ 100.`
 - `[output]` an integer
    The desired length.
def avoid_obstacles(arr):
  n=2
  while 1: 
    if all([x%n for x in arr]): return n
    n+=1
def avoid_obstacles(arr):
  n=2
  while 1: 
    if all([x%n for x in arr]): return n
    n+=1