import java.util.*;
import java.lang.Math;
class Main {
    static long maximumSum_simplified(int[] A) {
        int len = A.length;

        long[] maxSum = new long[len + 1];

        for (int start = 0, end; start < len - 1; start = end) {
            end = start + 1;
            if (A[end] <= A[start]) {
                while (end + 1 < len && A[end + 1] <= A[end]) end++;
                for (int i = Math.max(end - 1, start + 1); i <= end; i++) {
                    maxSum[i + 1] = Math.max(maxSum[start] + A[start] - A[i],
                            maxSum[start + 1] + A[start + 1] - A[i]);
                }
            } else {
                while (end + 1 < len && A[end + 1] >= A[end]) end++;
                for (int i = Math.max(end - 1, start + 1); i <= end; i++) {
                    maxSum[i + 1] = Math.max(maxSum[start] + A[i] - A[start],
                            maxSum[start + 1] + A[i] - A[start + 1]);
                }
            }
        }

        return maxSum[len];
    }
  public static void main(String[] args) {

    int[] a={8,1,7,9,2};
    System.out.println(maximumSum_simplified(a));


  }
}