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

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)

g=lcm(*a)-1

ans=0
for i in a:
    ans+=g%i

print(ans)
