import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


class Info {
  int[2] val, bef, pos;
  this() {
    val[] = 0;
    bef[] = -1;
    pos[] = -1;
  }
  override string toString() const {
    return format("(%s,%s,%s; %s,%s,%s)", val[0], bef[0], pos[0], val[1], bef[1], pos[1]);
  }
}

Info mul(const(Info) p, const(Info) q) {
  Info ret = new Info();
  int s = 0, t = 0;
  if (p.val[s] > q.val[t]) {
    ret.val[0] = p.val[s];
    ret.bef[0] = p.bef[s];
    ret.pos[0] = p.pos[s];
    ++s;
  } else {
    ret.val[0] = q.val[t];
    ret.bef[0] = q.bef[t];
    ret.pos[0] = q.pos[t];
    ++t;
  }
  for (; s < 2 || t < 2; ) {
    if (s < 2 && (t == 2 || p.val[s] > q.val[t])) {
      if (ret.bef[0] != p.bef[s]) {
        ret.val[1] = p.val[s];
        ret.bef[1] = p.bef[s];
        ret.pos[1] = p.pos[s];
        break;
      }
      ++s;
    } else {
      if (ret.bef[0] != q.bef[t]) {
        ret.val[1] = q.val[t];
        ret.bef[1] = q.bef[t];
        ret.pos[1] = q.pos[t];
        break;
      }
      ++t;
    }
  }
  return ret;
}

int segN;

void update(Info[] seg, int a, Info val) {
  a += segN;
  seg[a] = mul(seg[a], val);
  for (; a >>= 1; ) {
    seg[a] = mul(seg[a << 1], seg[a << 1 | 1]);
  }
}

alias Result = Tuple!(int, "val", int, "pos");

Result rangeMax(Info[] seg, int a, int b, int key) {
  Result ret = Result(0, -1);
  void check(int c) {
    const s = (seg[c].bef[0] != key) ? 0 : 1;
    chmax(ret, Result(seg[c].val[s], seg[c].pos[s]));
  }
  for (a += segN, b += segN; a < b; a >>= 1, b >>= 1) {
    if (a & 1) check(a++);
    if (b & 1) check(--b);
  }
  return ret;
}

void main() {
  try {
    for (; ; ) {
      const N = readInt();
      auto A = new int[N];
      foreach (i; 0 .. N) {
        A[i] = readInt();
      }
      
      debug {
        auto brt = new int[][](N, N);
        foreach (i; 0 .. N) {
          foreach (j; 0 .. i) {
            if (A[j] != A[i]) {
              chmax(brt[i][j], 2);
            }
            foreach (k; 0 .. j) {
              if (((A[k] < A[j] && A[j] > A[i]) || (A[k] > A[j] && A[j] < A[i])) && A[k] != A[i]) {
                chmax(brt[i][j], brt[j][k] + 1);
              }
            }
          }
        }
        writeln("brt = ");
        foreach (i; 0 .. N) {
          writeln(i, ": ", brt[i]);
        }
        int mx;
        foreach (i; 0 .. N) foreach (j; 0 .. i) {
          chmax(mx, brt[i][j]);
        }
        writeln("brute: ", (mx < 3) ? 0 : mx);
      }
      
      auto as = A.dup.sort.uniq.array;
      const asLen = cast(int)(as.length);
      for (segN = 1; segN < asLen; segN <<= 1) {}
      auto segU = new Info[segN << 1];
      auto segD = new Info[segN << 1];
      segU[] = new Info();
      segD[] = new Info();
      
      int ans;
      foreach (i; 0 .. N) {
        const pos = as.lowerBound(A[i]);
        Info dpU = new Info();
        const resD0 = segD.rangeMax(0, pos, pos);
        dpU.val[0] = resD0.val + 1;
        dpU.bef[0] = resD0.pos;
        dpU.pos[0] = pos;
        if (resD0.pos != -1) {
          const resD1 = max(segD.rangeMax(0, resD0.pos, pos), segD.rangeMax(resD0.pos + 1, pos, pos));
          dpU.val[1] = resD1.val + 1;
          dpU.bef[1] = resD1.pos;
          dpU.pos[1] = pos;
        }
        Info dpD = new Info();
        const resU0 = segU.rangeMax(pos + 1, asLen, pos);
        dpD.val[0] = resU0.val + 1;
        dpD.bef[0] = resU0.pos;
        dpD.pos[0] = pos;
        if (resU0.pos != -1) {
          const resU1 = max(segU.rangeMax(pos + 1, resU0.pos, pos), segU.rangeMax(resU0.pos + 1, asLen, pos));
          dpD.val[1] = resU1.val + 1;
          dpD.bef[1] = resU1.pos;
          dpD.pos[1] = pos;
        }
        segU.update(pos, dpU);
        segD.update(pos, dpD);
        chmax(ans, dpU.val[0]);
        chmax(ans, dpD.val[0]);
        debug {
          writeln(i, ": ", pos, " ", dpU, " ", dpD);
          // writeln("segU = ", segU);
          // writeln("segD = ", segD);
        }
      }
      writeln((ans < 3) ? 0 : ans);
    }
  } catch (EOFException e) {
  }
}