from functools import reduce
from math import gcd


N = int(input())
A = [int(a) for a in input().split()]
def lcm(a,b):
    return (a*b//gcd(a, b))
def lcmm(l):
    return reduce(lcm, l)

m = lcmm(A) - 1
print(sum([m%a for a in A]))