#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int N = 1e5 + 5;

int arr[N], f[N][3][2];

int main()
{
    int n;
    scanf("%d", &n);
    for (int i = 1; i <= n; ++i)
        scanf("%d", &arr[i]);
    memset(f, -0x3f, sizeof(f));
    f[1][0][0] = 0;
    f[1][1][1] = -arr[1];
    for (int i = 2; i <= n; ++i)
    {
        f[i][0][0] = 0;
        for (int j = 1; j <= 2; ++j)
        {
            f[i][j][0] = max(f[i-1][j][0], f[i-1][j][1]+arr[i]);
            f[i][j][1] = max(f[i-1][j][1], f[i-1][j-1][0]-arr[i]);
        }
    }

    int maxv = max(f[n][0][0], f[n][1][0]);
    printf("%d", max(maxv, f[n][2][0]));
    return 0;
}