import math

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

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

#aの最小公倍数を求める
lcm_t = a[0]

for j in range(1,N):
    lcm_t = lcm(lcm_t,a[j])

lcm_t = max(1,lcm_t-1)

ans = 0

for k in a:
    ans += lcm_t % k

print(ans)