import math
from functools import reduce
N = int(input())
a = [int(ai) for ai in input().split()]

def f(m):
    answer = 0
    for ai in a:
        answer += m % ai
    return answer

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

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

m = lcm(a) - 1
print(f(m))
