import statistics
import math
from functools import reduce

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

def lcm(*numbers):
    return reduce(lcm_base, numbers, 1)

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

n = int(input())
nums = list(map(int, input().split()))
lcm = lcm_list(nums)

# print(nums, lcm)
sum =0
for num in nums:
    sum += (lcm-1)%num
print(sum)
