import fraction as math

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

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

l = a[0]
for num in a[1:]:
    l = lcm(num, l)

ans = 0
for num in a:
    ans += (l - 1) % num

print(ans)

