import math
from functools import reduce

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

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

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

N = int(input())
a = list(map(int,input().split()))
m = lcm(*a) - 1
ans = 0
for i in range(N):
  ans += m%a[i]
print(ans)