Codeforces Round #162 (Div. 2) B. Roadside Trees (Simplified Edition)

题目：http://codeforces.com/contest/265/problem/B

 

#include <iostream>
#include <stdio.h>
#include <cstring>
#include <cmath>

using namespace std;

int arr[100000];
int main()
{
    int n;
    cin>>n;

    for(int i=0;i<n;i++)
    {
        cin >> arr[i];
    }
    int ans=2*n-1+arr[0];
    for(int i=0;i<n-1;i++)
    {
        ans+=(abs(arr[i+1]-arr[i]));
    }
    
    cout << ans;
        return 0;
}