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

N = int(input())
a = list(map(int, input().split()))
lcm2 = 1
for i in range(N):
    lcm2 = lcm(a[i], lcm2)
lcm2 -= 1
f = 0
for i in range(N):
    f += lcm2%a[i]
print(f)