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

#define rep(i, l, r) for (int i = (int)(l); i<(int)(r); i++)
#define ll long long

template<class T> bool chmin(T& a, T b) {if (a > b) {a = b; return 1;} return 0;}
template<class T> bool chmax(T& a, T b) {if (a < b) {a = b; return 1;} return 0;}

const int inf = 1e9;
const ll INF = 4e18;

int main() {
    int N; cin >> N;
    vector<ll> A(N);
    rep(i, 0, N) cin >> A[i];
    vector dp(N+1, vector(2, vector<ll>(2, -INF)));
    dp[0][0][0] = 0;
    rep(i, 0, N) {
        rep(f, 0, 2) rep(j, 0, 2) {
            if (j == 0) {
                chmax(dp[i+1][1][1-j], dp[i][f][j] - A[i]);
            }
            else {
                chmax(dp[i+1][1][1-j], dp[i][f][j] + A[i]);
            }
            chmax(dp[i+1][f][j], dp[i][f][j]);
        }
    }
    cout << max(dp[N][1][0], dp[N][1][1]) << endl;
}