N = int(input())
a = list(map(int, input().split()))
a.sort(reverse=True)

# ユークリッドの互除法により最大公約数を求める
ans = 0
val1, val2 = a[0], a[1]
while 1:
  if val1 % val2 == 0:
    ans = a[0]*a[1]/val2
    break
  else:
    tmp = val2
    val2 = val1 % val2
    val1 = tmp

for i in range(2, N):
  val1, val2 = ans, a[i]
  while 1:
    if val1 % val2 == 0:
      ans = ans*a[i]/val2
      break
    else:
      tmp = val2
      val2 = val1 % val2
      val1 = tmp

f_ans = 0
for i in range(N):
  f_ans += (ans-1)%a[i]
print(int(f_ans))
  
      
  