Problem:
Score : 300 points

Problem Statement

There is an integer sequence A of length N whose values are unknown.

Given is an integer sequence B of length N-1 which is known to satisfy the following:

B_i \geq \max(A_i, A_{i+1})

Find the maximum possible sum of the elements of A.

Constraints

All values in input are integers.

2 \leq N \leq 100

0 \leq B_i \leq 10^5

Input

Input is given from Standard Input in the following format:

N
B_1 B_2 ... B_{N-1}

Output

Print the maximum possible sum of the elements of A.

Sample Input 1

3
2 5

Sample Output 1

9

A can be, for example, ( 2 , 1 , 5 ), ( -1 , -2 , -3 ), or ( 2 , 2 , 5 ). Among those candidates, A = ( 2 , 2 , 5 ) has the maximum possible sum.

Sample Input 2

2
3

Sample Output 2

6

Sample Input 3

6
0 153 10 10 23

Sample Output 3

53

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

import java.util.*;

class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] b = new int[n-1];
        int min = Integer.MAX_VALUE;
        int sum = 0;
        int tmp = 0;
        for(int i = 0;i < n-1;i++){
            b[i] = sc.nextInt();
            if(min > b[i]){
                min = b[i];
                tmp = i;
            }
            sum += b[i];
        }

        try{
            int change = Math.max(b[tmp-1],b[tmp+1]);
            sum = sum + change - min;
        }catch(Exception ex){
            if(tmp == 0){
                sum = sum + b[1] - min;
            }else{
                sum = sum + b[n-1] - min;
            }
        }
        
        System.out.println(sum);
    }
}