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();
		Long[] A = new Long[N];
		Long first = sc.nextLong();
		A[0] = first;
		A[1] = first;
		Long second = 0L;
		for(int i=1;i<N-1;i++){
			second = sc.nextLong();
			if(A[i] > second){A[i]=second;}
			A[i+1] = second;
		}
		A[N-1] = (N==2)?first:second;
		Long Ans =0L;
		for(int i=0;i<N;i++){
			Ans += A[i];
		}
		System.out.println(Ans);
		sc.close();
	}
}