import math
from functools import reduce

N = int(input())
a = list(map(int, input().split()))

#最小公倍数-1
def lcm_base(x, y):
    return (x * y) // math.gcd(x, y)

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

MaxKoubai = lcm_list(a)
m = MaxKoubai - 1
result = 0

for i in range(N):
    result += m % a[i]
    
print(result)