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: Wrong Answer)

import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int n = sc.nextInt();

    int b[] = new int[n-1];
		for(int i = 0; i < n-1; i++){
			b[i] = sc.nextInt();
		}
    // System.out.println(n);

    int max = b[0];
    for (int i = 1; i < b.length; i++) {
      int v = b[i];
      if (v > max) {
          max = v;
      }
    }

    int a[] = new int[n];
    for(int i = 0; i < a.length; i++){
      a[i] = max;
    }

    for(int i = 0; i < b.length; i++){
      if(a[i] > b[i]){
        a[i] = b[i];
        a[i+1] = b[i];
      }
    }

    int sum = 0;
    for(int i = 0; i < a.length; i++){
      sum += a[i];
    }
		// 出力
		System.out.println(sum);
    // System.out.println(Arrays.toString(a));
	}
}