import math
n = int(input())
a = list(map(int, input().split()))

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

def lcm_list(numbers):
    a_0 = numbers.pop()
    for i in numbers:
        a_0 = lcm_base(a_0, i)
    return a_0

b = a.copy()
m = lcm_list(b)-1
sum = 0
for j in a:
    sum += m%j

print(sum)