import math

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

def f(m, a):
    re = 0
    for i in a:
        re += m % i
    return re

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)

m = lcm_list(a) - 1
print(f(m, a))