//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using vi = vector<ll>;
using vd = vector<ld>;
using vP = vector<P>;
using vvi = vector<vector<ll>>;
using vvd = vector<vector<ld>>;
using vvP = vector<vector<P>>;
using vvvi = vector<vector<vector<ll>>>;
using vvvd = vector<vector<vector<ld>>>;
using vvvP = vector<vector<vector<P>>>;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using Mint = modint1000000007;
using vm = vector<mint>;
using vM = vector<Mint>;
using vvm = vector<vector<mint>>;
using vvM = vector<vector<Mint>>;
using vvvm = vector<vector<vector<mint>>>;
using vvvM = vector<vector<vector<Mint>>>;
#endif
#define rrep(i, n) for (ll i = (n)-1; (i) >= 0; --(i))
#define rep(i, n) for (ll i = 0; (i) < (n); ++(i))
#define reps(i, n) for (ll i = 1; (i) <= (n); ++(i))
#define Rep(i,a,b) for(ll i = (a); i <= (b); i++)
#define all(a) (a).begin(),(a).end()
const ll MOD = 998244353;
#define Yes(b) ((b)?"Yes":"No")
#define YES(b) ((b)?"YES":"NO")
#define ft first
#define sd second
bool chmin(ll& a, ll b) { return a > b ? a = b, 1 : 0; }
bool chmax(ll& a, ll b) { return a < b ? a = b, 1 : 0; }
// array s90 = { 0, 1, 0, -1 }, c90 = { 1, 0, -1, 0 };
// array s45 = { 0, 1, 1, 1, 0, -1, -1, -1 }, c45 = { 1, 1, 0, -1, -1, -1, 0, 1 };

signed main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    ll N; cin >> N;
    vi a(N+1); reps(i, N) cin >> a[i];
    vvi dp(N+1, vi(2, -4e18)); dp[0][0] = 0;
    reps(i, N){
        dp[i][0] = max(dp[i-1][0], dp[i-1][1] + a[i]);
        dp[i][1] = max(dp[i-1][1], dp[i-1][0] - a[i]);
    }
    cout << max(dp[N][0], dp[N][1]) << endl;
}