#include <bits/stdc++.h>
using namespace std;
#define all(v) (v).begin(),(v).end()
#define pb(a) push_back(a)
#define rep(i, n) for(int i=0;i<n;i++)
#define foa(e, v) for(auto& e : v)
using ll = long long;
const ll MOD7 = 1000000007, MOD998 = 998244353, INF = (1LL << 60);
#define dout(a) cout<<fixed<<setprecision(10)<<a<<endl;

void chmax(ll &a, ll b) { a = max(a, b); }
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n; cin >> n;
    ll a;
    vector<ll> dp(2, -INF);
    rep(i, n) {
        cin >> a;
        auto nx = dp;
        chmax(nx[1], dp[0] - a);
        chmax(nx[0], dp[1] + a);

        swap(nx, dp);
        chmax(dp[1], -a);
    }
    cout << max(dp[0], dp[1]) << endl;
    return 0;
}