#include <bits/stdc++.h>
#define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
using namespace std;

typedef long long ll;

template <typename T> vector<T> make_zigzag(vector<T> a) {
    a.erase(unique(a.begin(), a.end()), a.end());
    int n = a.size();
    vector<T> ret;
    ret.push_back(a[0]);
    rep(i, 1, n - 1) {
        if (a[i - 1] > a[i] && a[i] > a[i + 1])
            continue;
        if (a[i - 1] < a[i] && a[i] < a[i + 1])
            continue;
        ret.push_back(a[i]);
    }
    ret.push_back(a[n - 1]);
    return ret;
}

int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, 0, n) cin >> a[i];
    ll dp[n + 1][2];
    rep(i, 0, n + 1) rep(j, 0, 2) dp[i][j] = -1e15;
    dp[0][0] = 0;
    rep(i, 0, n) {
        dp[i + 1][0] = max(dp[i + 1][0], dp[i][0]);
        dp[i + 1][0] = max(dp[i + 1][0], dp[i][1] + a[i]);
        dp[i + 1][1] = max(dp[i + 1][1], dp[i][1]);
        dp[i + 1][1] = max(dp[i + 1][1], dp[i][0] - a[i]);
    }
    ll ans = max(dp[n][0], dp[n][1]);
    if (ans == 0) {
        ans = -1e15;
        rep(i, 0, n) { ans = max(ans, (ll)-a[i]); }
    }
    cout << ans << endl;
}