
def gcd(x, y):
	if y == 0:
		return x
	else:
		return gcd(y, x % y)

N = int(input())
A = list(map(int, input().split()))
#N = 3
#A = [3,4,6]

t = A[0]
for i in range(1,N):
	t = t * A[i] / gcd(t, A[i])
sum = 0
t -= 1
#print(t)
for i in range(N):
	sum += t % A[i]
print(sum)
