from functools import reduce

n = int(input())
a = list(map(int, input().split()))

def gcd(a, b):
  if b == 0:
    return a
  else:
    return gcd(b, a % b)

def lcm_base(a, b):
  return a * b / gcd(a, b)

def lcm(n):
  return reduce(lcm_base, n)

f = 0
for i in a:
  f += (lcm(a) - 1) % i

print(int(f))
