Problem:
Score : 300 points

Problem Statement

You are given N positive integers a_1, a_2, ..., a_N.

For a non-negative integer m, let f(m) = (m\ mod\ a_1) + (m\ mod\ a_2) + ... + (m\ mod\ a_N).

Here, X\ mod\ Y denotes the remainder of the division of X by Y.

Find the maximum value of f.

Constraints

All values in input are integers.

2 \leq N \leq 3000

2 \leq a_i \leq 10^5

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the maximum value of f.

Sample Input 1

3
3 4 6

Sample Output 1

10

f(11) = (11\ mod\ 3) + (11\ mod\ 4) + (11\ mod\ 6) = 10 is the maximum value of f.

Sample Input 2

5
7 46 11 20 11

Sample Output 2

90

Sample Input 3

7
994 518 941 851 647 2 581

Sample Output 3

4527

Solution in Ruby (2.3.3) (judge verdict: Accepted)

class Array
  def lcm
    self.inject{|a,b| a.lcm(b)}
  end

  def gcd
    self.inject{|a,b| a.gcd(b)}
  end
end

n = gets.chomp.to_i
a = []
a = gets.chomp.split.map(&:to_i)

#p n 
#p a 
#p a.lcm
cnt = 0
t = a.lcm
#p t
for i in 0..a.length-1
    cnt += (t-1) % a[i]
    #p cnt
end
puts cnt