#include <iostream>
#include <cstring>
using namespace std;
const int N = 1e5 + 10;
int n;
int w[N];
int f[2][3];
int main()
{
cin >> n;
for (int i = 1; i <= n; ++ i) cin >> w[i];
memset(f, -0x3f, sizeof f);
f[0][0] = 0;
for (int i = 1; i <= n; ++ i)
{
f[i & 1][0] = max(f[(i - 1) & 1][0], f[(i - 1) & 1][2]);
f[i & 1][1] = max(f[(i - 1) & 1][1], f[(i - 1) & 1][0] - w[i]);
f[i & 1][2] = f[(i - 1) & 1][1] + w[i];
}
cout << max(f[n & 1][0], f[n & 1][2]) << endl;
return 0;
}