[백준] 2847번 : 게임을 만든 동준이 - C#

https://www.acmicpc.net/problem/2847

using System;

class Program
{
    static void Main() {
        string s=Console.ReadLine();
        int n=int.Parse(s);
        int[] arr=new int[n];
        int count=0;
        for(int i=0;i<n;i++){
            string s1=Console.ReadLine();
            arr[i]=int.Parse(s1);
        }
        for(int i=n-1;i>0;i--){
            if(arr[i]<=arr[i-1]){
                count+=arr[i-1]-arr[i]+1;
                arr[i-1]=arr[i]-1;
            }
        }
        Console.Write(count);
    }
}