output_description: Print the minimum number of watering operations required to satisfy the
  condition.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      h_1 h_2 h_3 ...... h_N
attempt: #! /usr/bin/env python3
  # -*- coding: utf-8 -*-
  N = input()
  h = "".join(input().split()) # h は数字の文字列
  count = 0
  while sum([int(x) for x in h]) != 0:
      h2 = [x for x in h.strip("0").split("0")]
      count += len(h2)
      h3 = ""join.h2
      h = [int(x)-1 for x in h3]
  
  print(count)
problem_description: Statement
  
  In a flower bed, there are N flowers, numbered 1,2,......,N. Initially, the
  heights of all flowers are 0. You are given a sequence
  h=\\{h_1,h_2,h_3,......\\} as input. You would like to change the height of
  Flower k to h_k for all k (1 \leq k \leq N), by repeating the following
  "watering" operation:
  
    * Specify integers l and r. Increase the height of Flower x by 1 for all x such that l \leq x \leq r.
  
  Find the minimum number of watering operations required to satisfy the
  condition.
samples: [{"input": "4\n    1 2 2 1", "output": "2\n    \n\nThe minimum number of watering operations required is 2. One way to achieve it\nis:\n\n  * Perform the operation with (l,r)=(1,3).\n  * Perform the operation with (l,r)=(2,4).\n\n* * *"}, {"input": "5\n    3 1 2 3 1", "output": "5\n    \n\n* * *"}, {"input": "8\n    4 23 75 0 23 96 50 100", "output": "221"}]