from sys import stdin
import math

N = int(stdin.readline().rstrip())
A = [int(x) for x in stdin.readline().rstrip().split()]

lcm_a = int(A[0] * A[1] / math.gcd(A[0], A[1]))

for k in A[2:]:
    lcm_a = int(lcm_a * k / math.gcd(lcm_a, k))

modulo_sum = 0

for k in A:
    modulo_sum += (lcm_a - 1) % k

print(modulo_sum)
