#include <bits/stdc++.h>
using namespace std;

using lint = long long;

lint INF = 1000000000000000000;

int main() {
    int n;
    cin >> n;
    vector<lint> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    vector<vector<lint>> dp(n + 1, vector<lint>(2, -INF));
    dp[0][0] = 0;
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j < 2; j++) {
            dp[i][j] = max(dp[i][j], dp[i - 1][j]);
            lint mul = (j == 0 ? 1LL : -1LL);
            dp[i][j] = max(dp[i][j], dp[i - 1][1 - j] + a[i - 1] * mul);
        }
    }
    lint ans = -INF;
    for (int i = 0; i < n; i++) {
        for(int j = 0; j < 2; j++) {
            lint mul = (j == 0 ? 1LL : -1LL);
            lint cur = dp[i][1 - j] + a[i] * mul;
            ans = max(ans, cur);
        }
    }
    cout << ans << endl;
}