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

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    vector<int> A(N);
    for(auto &a : A) cin >> a;

    long long minus = 0,plus = -1e18;
    for(int i=0; i<N; i++){
        long long nm = -1e19,np = -1e18;
        nm = max(minus,plus+A.at(i));
        np = max(plus,minus-A.at(i));
        swap(minus,nm); swap(plus,np);
    }
    cout << max(minus,plus) << endl;
}