import std.algorithm, std.conv, std.range, std.stdio, std.string;

void main()
{
  auto n = readln.chomp.to!size_t;
  auto ai = readln.split.to!(int[]);

  auto calc = new Calc(n, ai);
  auto r = n.iota.map!(i => [calc.calcA(i, n-1), calc.calcB(i, 0)]).joiner.maxElement;
  writeln(r);
}

class Calc
{
  size_t n;
  int[] ai;
  int[][] dpa, dpb;

  this(size_t n, int[] ai)
  {
    this.n = n;
    this.ai = ai;
    dpa = new int[][](n, n);
    dpb = new int[][](n, n);
  }

  int calcA(size_t i, size_t m)
  {
    if (dpa[i][m]) return dpa[i][m];

    auto a = ai[i], b = int.max, r = 0;

    foreach_reverse (j; i+1..m+1)
      if (ai[j] > a && ai[j] < b) {
        b = ai[j];
        r = max(r, calcB(j, i+1));
      }

    return dpa[i][m] = r + 1;
  }

  int calcB(size_t i, size_t m)
  {
    if (dpb[i][m]) return dpb[i][m];

    auto a = ai[i], b = int.max, r = 0;

    foreach (j; m..i)
      if (ai[j] > a && ai[j] < b) {
        b = ai[j];
        r = max(r, calcA(j, i-1));
      }

    return dpb[i][m] = r + 1;
  }
}