#include <iostream>

using namespace std;

const int N = 1e5 + 10;
const int INF = 1e9 + 10;

int w[N];

// 没股票
int f[N];
// 有股票
int g[N];

int main() {
    int n;
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        cin >> w[i];
    }

    g[0] = -INF;
    for (int i = 1; i <= n; ++i) {
        f[i] = max(f[i - 1], g[i - 1] + w[i]);
        g[i] = max(g[i - 1], f[i - 1] - w[i]);
    }

    cout << f[n] << endl;

    return 0;
}