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 C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

class Program
{
    static void Main(string[] args)
    {
        string N = Console.ReadLine();
        List<int> a = Console.ReadLine().Split(' ').Select(int.Parse).ToList();

        decimal LowestCommonMultiple = 1;
        int GreatestCommonFactor = 1;

        for (int i = a.Min() / 2; 0 < i; i--)
        {
            for(int j = 0; j < a.Count; j++)
            {
                if(a[j] % i != 0)
                {
                    goto Next;
                }                    
            }
            GreatestCommonFactor = i;
            break;

            Next:;
        }
            
        for(int i = 0; i < a.Count; i++)
        {
            LowestCommonMultiple *= a[i] / GreatestCommonFactor;
        }

        decimal val = 0;
        for(int j = 0; j < a.Count; j++)
        {
            val += (LowestCommonMultiple - (decimal)1) % (decimal)a[j]; 
        }
            
        Console.WriteLine(val);
    }
}