#include <bits/stdc++.h>

using namespace std;
using ll = long long;

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

    ll N;
    cin >> N;
    vector<ll> A(N+1);
    for (int i=1; i<=N; i++) cin >> A[i];
    vector dp(N+1, vector<ll>(2, -1e18));
    dp[0][0] = 0;
    for (int i=1; i<=N; i++){
        dp[i][1] = max(dp[i-1][0]-A[i], dp[i-1][1]);
        dp[i][0] = max(dp[i-1][1]+A[i], dp[i-1][0]);
    }

    cout << max(dp[N][1], dp[N][0]) << endl;

    return 0;
}