#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n;
  cin >> n;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  vector dp(n + 1, vector<ll>(2, -1e18));
  dp[0][0] = 0;
  rep(i, n) {
    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]);
  }
  cout << max(dp[n][0], dp[n][1]) << '\n';
  return 0;
}