import math
import fraction
from functools import reduce


def lcm_base(x, y):
    return (x * y) // math.gcd(x, y)


def lcm_list(numbers):
    return reduce(lcm_base, numbers, 1)


n = int(input())
a = [int(i) for i in input().split()]

ans1 = 0

lcm = lcm_list(a)

for num in a:
    ans1 += (lcm - 1) % num

print(ans1)
