output_description: Print the maximum value of f.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      a_1 a_2 ... a_N
attempt: 
  def gcd(x, y):
  	if y == 0:
  		return x
  	else:
  		return gcd(y, x % y)
  
  N = int(input())
  A = list(map(int, input().split()))
  #N = 7
  #A = [994, 518, 941, 851, 647, 2, 581]
  t = A[0]
  for i in range(1,N):
  	if (t % A[i])
  		continue
  	t = t * A[i] / gcd(t, A[i])
  sum = 0
  t -= 1
  for i in range(N):
  	sum += t % A[i]
  print(int(sum))
  
problem_description: Statement
  
  You are given N positive integers a_1, a_2, ..., a_N.
  
  For a non-negative integer m, let f(m) = (m\ mod\ a_1) + (m\ mod\ a_2) + ... +
  (m\ mod\ a_N).
  
  Here, X\ mod\ Y denotes the remainder of the division of X by Y.
  
  Find the maximum value of f.
samples: [{"input": "3\n    3 4 6", "output": "10\n    \n\nf(11) = (11\\ mod\\ 3) + (11\\ mod\\ 4) + (11\\ mod\\ 6) = 10 is the maximum value\nof f.\n\n* * *"}, {"input": "5\n    7 46 11 20 11", "output": "90\n    \n\n* * *"}, {"input": "7\n    994 518 941 851 647 2 581", "output": "4527"}]