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

void fast_io() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
}

int main() {
	fast_io();
	int n;
	cin >> n;
	vector<long long> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	long long INF = 1e18;
	vector<vector<long long>> dp(2, vector<long long>(2, -INF));
	dp[0][0] = 0;
	for (int i = 0; i < n; i++) {
		vector<vector<long long>> new_dp = dp;
		new_dp[0][1] = max({dp[0][1], dp[1][0] + a[i], dp[1][1] + a[i]});
		new_dp[1][1] = max({dp[1][1], dp[0][0] - a[i], dp[0][1] - a[i]});
		swap(dp, new_dp);
	}
	cout << max(dp[0][1], dp[1][1]) << endl;
}