import math

def lcm(a, b):
    return (a * b) // math.gcd(a,  b)

def lcm_list(li):
    if len(li) == 2:
        return lcm(li[0], li[1])
    else:
        li = [lcm(li[0], li[1])] + li[2:]
        return  lcm_list(li)

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


i = lcm_list(a) -1
print(sum([i%j for j in a]))