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.*;

public class Main {
    void run() {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();
        long[] aArr = new long[n];

        for (int i = 0; i < n; i++) {
            aArr[i] = sc.nextLong();
        }

        long absMin = Integer.MAX_VALUE;
        long sum = 0;
        for (int i = 0; i < n; i++) {
            absMin = Math.min(absMin, Math.abs(aArr[i]));
            sum += Math.abs(aArr[i]);
        }

        System.out.println(condition(aArr, n) ? sum : sum - 2 * absMin);
    }

    boolean condition(long[] aArr, int n) {
        // 全部+にできればtrue
        int plusCount = 0;
        for (int i = 0; i < n; i++) {
            if (aArr[i] > 0) plusCount++;
        }
        return (n % 2 == 0 && plusCount % 2 == 0) || (n % 2 != 0 && plusCount % 2 != 0);
    }

    void debug(Object... os) {
        System.err.println(Arrays.deepToString(os));
    }

    public static void main(String[] args) {
        new Main().run();
    }
}
