import java.io.*;
class Main{

    static BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
    static int N = 100010, INF = 0x3f3f3f3f;
    static int[][][] dp = new int[N][3][2];
    public static void main(String[] args) throws Exception{
        int n = Integer.valueOf(read.readLine());
        int[] a = new int[n + 1];
        String[] ss = read.readLine().split(" ");
        for(int i = 1; i <= n; i++){
            a[i] = Integer.valueOf(ss[i - 1]);
        }
        for(int i = 0; i <= n; i++){
            for(int j = 0; j <= 2; j++){
                dp[i][j][0] = -INF;
                dp[i][j][1] = -INF;
            }
        }
        for(int i = 0; i <= n; i++) dp[i][0][0] = 0;   //注意初始化， 这里容易出错



        for(int i = 1; i <= n; i++){
            for(int k = 1; k <= 2; k++){
                dp[i][k][0] = Math.max(dp[i - 1][k][0], dp[i - 1][k][1] + a[i]);
                dp[i][k][1] = Math.max(dp[i - 1][k][1], dp[i - 1][k - 1][0] - a[i]);
            }
        }
        int max = 0;
        for(int k = 0; k <= 2; k++){
            max = Math.max(max, dp[n][k][0]);
        }
        System.out.println(max);

    }

}