#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) cin >> a[i];
  vector<vector<long long>> dp(n + 1, vector<long long> (2, -1e18));
  dp[0][0] = 0;
  for (int i = 0; i < n; ++i)
  {
    dp[i + 1][0] = max(dp[i][0], dp[i][1] + a[i]);
    dp[i + 1][1] = max(dp[i][1], dp[i][0] - a[i]);
  }
  long long ans = max(dp[n][0], dp[n][1]);
  auto b = a;
  sort(b.rbegin(), b.rend());
  if (a == b)
  {
    ans = -1e18;
    for (int i = 0; i < n - 1; ++i) ans = max(ans, (long long)a[i + 1] - a[i]);
  }
  cout << ans << endl;
}