Artem has an array of n positive integers. Artem decided to play with it. The game consists of n moves. Each move goes like this. Artem chooses some element of the array and removes it. For that, he gets min(a, b) points, where a and b are numbers that were adjacent with the removed number. If the number doesn't have an adjacent number to the left or right, Artem doesn't get any points. 

After the element is removed, the two parts of the array glue together resulting in the new array that Artem continues playing with. Borya wondered what maximum total number of points Artem can get as he plays this game.

Input

The first line contains a single integer n (1 ≤ n ≤ 5·105) — the number of elements in the array. The next line contains n integers ai (1 ≤ ai ≤ 106) — the values of the array elements.

Output

In a single line print a single integer — the maximum number of points Artem can get.

Examples

Input

5
3 1 5 2 6


Output

11


Input

5
1 2 3 4 5


Output

6


Input

5
1 100 101 100 1


Output

102
9
72 49 39 50 68 35 75 94 56
 4
2 3 1 2
 8
3 4 3 1 1 3 4 1
 1
4
 7
2 1 2 2 2 2 2
 6
1 7 3 1 6 2
 8
77 84 26 34 17 56 76 3
 2
93 51
 1
87
 4
86 21 58 60
 10
96 66 8 18 30 48 34 11 37 42
 6
46 30 38 9 65 23
 5
21 6 54 69 32
 3
1 2 1
 3
31 19 5
 10
4 2 2 4 1 2 2 4 2 1
 7
82 60 92 4 2 13 15
 9
4 5 2 2 3 1 3 3 5
 5
2 6 2 1 2
 2
3 1

435 4 15 0 10 12 279 0 0 118 299 145 74 1 5 21 129 23 6 0
//package prac;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Comparator;
import java.util.InputMismatchException;

public class R253C {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		int n = ni();
		int[] a = na(n);
		int[] ft = new int[n+1];
		for(int i = 0;i < n;i++){
			addFenwick(ft, i, 1);
		}
		int[][] b = new int[n][];
		for(int i = 0;i < n;i++){
			b[i] = new int[]{a[i], i};
		}
		Arrays.sort(b, new Comparator<int[]>() {
			public int compare(int[] a, int[] b) {
				return a[0] - b[0];
			}
		});
		long ret = 0;
		int left = 0, right = n-1;
		for(int i = 0;i < n-2;i++){
			if(b[i][1] == left){
				ret += b[i][0];
				left++;
			}else if(b[i][1] == right){
				ret += b[i][0];
				right--;
			}else{
				break;
			}
		}
		
		int[][] c = new int[right-1-(left+1)+1][];
		for(int i = left+1;i < right;i++){
			c[i-left-1] = new int[]{a[i], i};
		}
		Arrays.sort(c, new Comparator<int[]>() {
			public int compare(int[] a, int[] b) {
				return a[0] - b[0];
			}
		});
		
		for(int[] x : c){
			addFenwick(ft, x[1], -1);
			int aft = after(ft, x[1]);
			int bef = before(ft, x[1]);
			ret += Math.min(a[bef], a[aft]);
		}
		out.println(ret);
	}
	
	public static int sumFenwick(int[] ft, int i)
	{
		int sum = 0;
		for(i++;i > 0;i -= i&-i)sum += ft[i];
		return sum;
	}
	
	public static void addFenwick(int[] ft, int i, int v)
	{
		if(v == 0 || i < 0)return;
		int n = ft.length;
		for(i++;i < n;i += i&-i)ft[i] += v;
	}
	
	public static int findGFenwick(int[] ft, int v)
	{
		int i = 0;
		int n = ft.length;
		for(int b = Integer.highestOneBit(n);b != 0 && i < n;b >>= 1){
			if(i + b < n){
				int t = i + b;
				if(v >= ft[t]){
					i = t;
					v -= ft[t];
				}
			}
		}
		return v != 0 ? -(i+1) : i-1;
	}
	
	public static int valFenwick(int[] ft, int i)
	{
		return sumFenwick(ft, i) - sumFenwick(ft, i-1);
	}
	
	public static int[] restoreFenwick(int[] ft)
	{
		int n = ft.length-1;
		int[] ret = new int[n];
		for(int i = 0;i < n;i++)ret[i] = sumFenwick(ft, i);
		for(int i = n-1;i >= 1;i--)ret[i] -= ret[i-1];
		return ret;
	}
	
	public static int before(int[] ft, int x)
	{
		int u = sumFenwick(ft, x-1);
		if(u == 0)return -1;
		return findGFenwick(ft, u-1)+1;
	}
	
	public static int after(int[] ft, int x)
	{
		int u = sumFenwick(ft, x);
		int f = findGFenwick(ft, u);
		if(f+1 >= ft.length-1)return -1;
		return f+1;
	}
	
	void run() throws Exception
	{
		is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		tr(System.currentTimeMillis()-s+"ms");
	}
	
	public static void main(String[] args) throws Exception { new R253C().run(); }
	
	private byte[] inbuf = new byte[1024];
	private int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
	private void tr(Object... o) { if(!oj)System.out.println(Arrays.deepToString(o)); }
}
