There are N integers, A_1, A_2, ..., A_N, arranged in a row in this order.

You can perform the following operation on this integer sequence any number of times:

Operation: Choose an integer i satisfying 1 \leq i \leq N-1. Multiply both A_i and A_{i+1} by -1.

Let B_1, B_2, ..., B_N be the integer sequence after your operations.

Find the maximum possible value of B_1 + B_2 + ... + B_N.

Constraints

* All values in input are integers.
* 2 \leq N \leq 10^5
* -10^9 \leq A_i \leq 10^9

Input

Input is given from Standard Input in the following format:


N
A_1 A_2 ... A_N


Output

Print the maximum possible value of B_1 + B_2 + ... + B_N.

Examples

Input

3
-10 5 -4


Output

19


Input

5
10 -4 -8 -11 3


Output

30


Input

11
-1000000000 1000000000 -1000000000 1000000000 -1000000000 0 1000000000 -1000000000 1000000000 -1000000000 1000000000


Output

10000000000


import java.util.Scanner;

public class Main {

	public static void main(String args[])
	{
		Scanner scan=new Scanner(System.in);
		int n=scan.nextInt();
		long ar[]=new long[n+1];
		long[][] sumtill=new long[100001][2];
		
		for(int i=1;i<=n;i++)
		{
			ar[i]=scan.nextLong();
		}
		sumtill[1][0]=ar[1];
		sumtill[1][1]=ar[1];
		sumtill[2][1]=-ar[1]-ar[2];
		sumtill[2][0]=ar[1]+ar[2];
		for(int i=3;i<=n;i++)
		{
			long maxwithout=Math.max(sumtill[i-2][0],sumtill[i-2][1]);
			
			sumtill[i][0]=ar[i]+Math.max(ar[i-1]+maxwithout,sumtill[i-1][1]);
			sumtill[i][1]=-ar[i]+Math.max(-ar[i-1]+maxwithout,sumtill[i-1][1]+2*ar[i-1]);
			
		}
		long answer=Math.max(sumtill[n][0],sumtill[n][1]);
		System.out.println(answer);
		
	}
}
