#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 inf = 1e18;
    vector<long long> dp1(N+1,-inf),dp2(N+1,-inf);
    dp1.at(0) = 0;
    for(int i=0; i<N; i++){
        dp1.at(i+1) = max(dp1.at(i),dp2.at(i)+A.at(i));
        dp2.at(i+1) = max(dp2.at(i),dp1.at(i)-A.at(i));
    }
    cout << max(dp1.back(),dp2.back()) << endl;
}