#include<iostream>
using namespace std;

int main()
{
	int n,b[100],i,ans=0,num=100000;

	cin>>n;
	for(i=0;i<n-1;i++){
		cin>>b[i];

		if(num<b[i]){
			ans+=num;
		}else{
			ans+=b[i];
		}

		num=b[i];
	}

	ans+=num;

	cout<<ans<<endl;

	return 0;
}
### Prompt

Create a solution in cpp for the following problem:

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

### Response

```cpp
#include<iostream>
using namespace std;

int main()
{
	int n,b[100],i,ans=0,num=100000;

	cin>>n;
	for(i=0;i<n-1;i++){
		cin>>b[i];

		if(num<b[i]){
			ans+=num;
		}else{
			ans+=b[i];
		}

		num=b[i];
	}

	ans+=num;

	cout<<ans<<endl;

	return 0;
}
```