# coding: utf-8
# Your code here!
n=int(input())
a=[int(x) for x in input().split()]
import math
def prod(lists):
    ans=1
    for i in lists:
        ans=ans*i
    return ans
def gcd(numbers):
    ans=numbers[0]
    for i in numbers:
        ans=math.gcd(ans,i)
    return ans
lcm=prod(a)//gcd(a)
print(sum([(lcm-1)%ai for ai in a]))