#include <bits/stdc++.h>

using namespace std;
#define fast_io ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
#define pb push_back
#define int long long
#define ll long long
#define ld long double

#define rep(i, n) for (ll i=0; i<n; i++)
#define repi(i, n) for (ll i=1; i<=n; i++)

#define repi1(i, n) for (ll i = n; i >=0; i--)
#define mem(v, ha) memset(v, ha, sizeof(v))
#define all(a)  a.begin(), a.end()
#define allr(a)  a.rbegin(), a.rend()
#define CLOCK cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
typedef vector<ll> vi;
typedef vector<vector<int>> vvi;
typedef vector<pair<ll, ll>> vpi;
typedef vector<char> vc;
#define no cout << "No\n"
#define yes cout << "Yes\n"
#define mp make_pair
#define ff first
#define ss second
const ll MOD = 1e9 + 7;
//const ll mod = 998244353 ;

const long double PI = 3.141592653589793238460;
const int inf = (int)(1e9);

template<typename T> istream& operator>>(istream& in, vector<T>& a) {for (auto &x : a) in >> x; return in;};
template<typename T> ostream& operator<<(ostream& out, vector<T>& a) {for (auto &x : a) out << x << ' '; return out;};


// auto sum=[&](int use, int y){return use+y;};
// function <void(int)>dfs=[&](int u)
//void is the return type, int is the argument
// sort(os.begin() , os.end() , [&](int i , int j) {
// 		return str[i] < str[j];
// 	});

void solve()
{
	int n;
	cin >> n;
	vector<int> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}

	vector<vector<int>> dp(n, vector<int>(2, 0));
	dp[0][0] = max(0ll, a[0]);  
	dp[0][1] = max(0ll, -a[0]);
	int max_score = max(dp[0][0], dp[0][1]);

	for (int i = 1; i < n; i++) {
		dp[i][0] = max({dp[i - 1][0], a[i], dp[i - 1][1] + a[i]});

		dp[i][1] = max({dp[i - 1][1], -a[i], dp[i - 1][0] - a[i]});

		max_score = max({max_score, dp[i][0], dp[i][1]});
	}

	cout << max_score << '\n';

}
int32_t main()
{
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("out.txt", "w", stdout);
#endif

	fast_io;
	int T = 1;
	// cin >> T;

	while (T--)
	{
		solve();


	}

}