import math
import functools


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

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

def lcm_list(*numbers):
    return functools.reduce(lcm_base, numbers, 1)

def main() :
    n = int(input())
    a = list(map(int, input().split()))
    lcm = lcm_list(*a)

    ans = 0
    for aa in a :
        ans += (lcm-1) % aa

    print(ans)

main()