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.

Examples

Input

3
2 5


Output

9


Input

2
3


Output

6


Input

6
0 153 10 10 23


Output

53
import java.util.*;
public class Main{
	public static void main(String[] args){
	  Scanner sc = new Scanner(System.in);
	  int n = sc.nextInt();
	  int[] b = new int[n-1];
	  
	  for(int i=0;i<n-1;i++)b[i]=sc.nextInt();
	  int ans = b[0];
	  for(int i = 1;i<n-1;i++){
	  	if(b[i-1]<b[i]){
          ans+=b[i-1];
        }else ans+=b[i];
	  }

	  ans += b[n-2];
	  
	  System.out.println(ans);
	}
}