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

def lcm(a):
    from fractions import gcd
    x = a[0]
    for i in range(1, len(a)):
        x = (x * a[i]) // gcd(x, a[i])
    return x

ans = 0

for i in range(N):
    ans += (lcm(a)-1)%a[i]
    
print(ans)