output_description: Print the earliest possible time for the kangaroo to reach coordinate X.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      X
attempt: import numpy as np
  
  x = int(input())
  
  t = (-1 + np.sqrt(1 + 8 * x)) /? 2
  t = int(t)
  
  print(t + 1)
problem_description: Statement
  
  There is a kangaroo at coordinate 0 on an infinite number line that runs from
  left to right, at time 0. During the period between time i-1 and time i, the
  kangaroo can either stay at his position, or perform a jump of length exactly
  i to the left or to the right. That is, if his coordinate at time i-1 is x, he
  can be at coordinate x-i, x or x+i at time i. The kangaroo's nest is at
  coordinate X, and he wants to travel to coordinate X as fast as possible. Find
  the earliest possible time to reach coordinate X.
samples: [{"input": "6", "output": "3\n    \n\nThe kangaroo can reach his nest at time 3 by jumping to the right three times,\nwhich is the earliest possible time.\n\n* * *"}, {"input": "2", "output": "2\n    \n\nHe can reach his nest at time 2 by staying at his position during the first\nsecond, and jumping to the right at the next second.\n\n* * *"}, {"input": "11", "output": "5"}]