#include <bits/stdc++.h>

using namespace std;
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
int n;
int w[N];
int f[N][2];//考虑前i天的股市，第i天的手中股票状态为j(j=0 未持股，j=1 持股)

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++)cin >> w[i];
    //base case
    f[1][0] = 0;
    f[1][1] = -w[1];
    for (int i = 2; i <= n; i++) {
        f[i][0] = max(f[i - 1][0], f[i - 1][1] + w[i]);
        f[i][1] = max(f[i - 1][1], f[i - 1][0] - w[i]);
    }
    printf("%d\n", f[n][0]);
    return 0;
}