#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main(void) {
    int n;
    cin >> n;

    vector<ll> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];

    vector<vector<ll>> dp(n+1,vector<ll>(2,LLONG_MIN/2));
    dp[0][0] = 0;
    for (int i = 0; i < n; i++) {
        dp[i+1][0] = max(dp[i+1][0],dp[i][0]);
        dp[i+1][1] = max(dp[i+1][1],dp[i][1]);

        dp[i+1][0] = max(dp[i+1][0],dp[i][1]+a[i]);
        dp[i+1][1] = max(dp[i+1][1],dp[i][0]-a[i]);
    }

    cout << max(dp[n][0],dp[n][1]) << endl;
    
    return 0;
}