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: N = int(input())
  Hlst = list(map(int, input().split()))
  times = 0
  l = 0
  r = l
  while r <= N:
      l = r
      while Hlst[r] == 1:
          r += 1
      for water in range(l, r + 1):
          Hlst[water] -= 1
          times += 1
  print(times)
  
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"}]