import functools
import fraction

def blcm(x, y):
	return (x*y)//fraction.gcd(x, y)

def slcm(numbers):
	return functools.reduce(blcm, numbers)
	
input()
numbers=list(map(int, input().split()))
num=slcm(numbers)-1
nums=[num%i for i in numbers]
print(sum(nums))
