import std.algorithm, std.container, std.conv, std.math, std.range, std.typecons, std.stdio, std.string;

auto rdsp(){return readln.splitter;}
void pick(R,T)(ref R r,ref T t){t=r.front.to!T;r.popFront;}
void readV(T...)(ref T t){auto r=rdsp;foreach(ref v;t)pick(r,v);}
void readA(T)(size_t n,ref T[]t){t=new T[](n);auto r=rdsp;foreach(ref v;t)pick(r,v);}

void main()
{
  int n; readV(n);
  int[] a; readA(n, a);

  auto dp = new long[][](n, n);
  foreach (i; 0..n)
    dp[i][i] = (n%2 == 1 ? 1 : -1) * a[i];

  foreach (j; 0..n)
    foreach_reverse (i; 0..j)
      if ((n-(j-i+1))%2 == 0)
        dp[i][j] = max(dp[i+1][j]+a[i], dp[i][j-1]+a[j]);
      else
        dp[i][j] = min(dp[i+1][j]-a[i], dp[i][j-1]-a[j]);

  writeln(dp[0][n-1]);
}
