#include <iostream>
#include <cassert>
#include <vector>
#include <algorithm>
using namespace std;
using ll = long long;

int main() {
	int n;
	cin >> n;
	vector<int> a(n);
	for (int i = 0; i < n; ++i) cin >> a[i];
	
	assert(1 <= n && n <= 200000);
	for (int i = 0; i < n; ++i) assert(abs(a[i]) <= 1000'000'000);
	
	vector<vector<ll>> dp(n+1, vector<ll>(3));
	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][2] - a[i], dp[i][0] - a[i]});
		dp[i+1][2] = max(dp[i][2], dp[i][1] + a[i]);
	}
	cout << max(dp[n][1], dp[n][2]) << endl;
}