import java.io.*;
import java.math.*;
import java.util.*;

import static java.util.Arrays.*;

public class Main {
	private static final int mod = (int)1e9+7;

	final Random random = new Random(0);
	final IOFast io = new IOFast();

	/// MAIN CODE
	public void run() throws IOException {
//		int TEST_CASE = Integer.parseInt(new String(io.nextLine()).trim());
		int TEST_CASE = 1;
		while(TEST_CASE-- != 0) {
			int n = io.nextInt();
			int[] A = io.nextIntArray(n);
			int[][] beam = new int[250][3];	// ans/prev/prev2
			int[][] beam2 = new int[2*beam.length][3];	// ans/prev/prev2
			int len = 0;
			beam[len][0] = 1;
			beam[len][1] = A[0];
			beam[len++][2] = 0;
			beam[len][0] = 1;
			beam[len][1] = A[0];
			beam[len++][2] = Integer.MAX_VALUE;
			HashTableLong h = new HashTableLong();
			for(int i = 1; i < n; i++) {
				int len2 = 0;
				h.clear();
				for(int j = 0; j < len; j++) {
					if(beam[j][2] != A[i] && beam[j][1] != A[i]) {
						if(beam[j][1] > beam[j][2] && beam[j][1] > A[i]) {
							if(h.get((long)A[i]<<32|beam[j][1]) < beam[j][0] + 1) {
								beam2[len2][0] = beam[j][0] + 1;
								beam2[len2][1] = A[i];
								beam2[len2++][2] = beam[j][1];
								h.put((long)A[i]<<32|beam[j][1], beam2[len2][0]);
							}
						}
						if(beam[j][1] < beam[j][2] && beam[j][1] < A[i]) {
							if(h.get((long)A[i]<<32|beam[j][1]) < beam[j][0] + 1) {
								beam2[len2][0] = beam[j][0] + 1;
								beam2[len2][1] = A[i];
								beam2[len2++][2] = beam[j][1];
								h.put((long)A[i]<<32|beam[j][1], beam2[len2][0]);
							}
						}
					}
					if(h.get((long)beam[j][1]<<32|beam[j][2]) < beam[j][0]) {
						beam2[len2][0] = beam[j][0];
						beam2[len2][1] = beam[j][1];
						beam2[len2++][2] = beam[j][2];
					}
				}
				Arrays.sort(beam2, 0, len2, (a,b)->b[0]-a[0]);
				len = 0;
				for(int j = 0; j < beam.length; j++) {
					beam[len][0] = beam2[j][0];
					beam[len][1] = beam2[j][1];
					beam[len++][2] = beam2[j][2];
				}
			}
			io.out.println(beam[0][0] < 3 ? 0 : beam[0][0]);
		}
	}
	
	static
	class HashTableLong {
		int gid;
		int[] id = new int[1<<22];
		int[] table = new int[1<<22];
		
		void clear() { gid++; }
		long get(long x) {
//			int idx = (int)(((x >>> 32) ^ (x)) & ((1<<22)-1));
			int idx = (int)((x * 27482423749238402L + 48374285234982434L) & ((1<<22)-1));
			return id[idx]==gid?table[idx]:0;
		}
		void put(long x, int v) {
			int idx = (int)((x * 27482423749238402L + 48374285234982434L) & ((1<<22)-1));
			id[idx] = gid;
			table[idx] = v;
		}
	}
	
	/// TEMPLATE
	static int gcd(int n, int r) { return r == 0 ? n : gcd(r, n%r); }
	static long gcd(long n, long r) { return r == 0 ? n : gcd(r, n%r); }
	
	static <T> void swap(T[] x, int i, int j) { T t = x[i]; x[i] = x[j]; x[j] = t; }
	static void swap(int[] x, int i, int j) { int t = x[i]; x[i] = x[j]; x[j] = t; }
	
	void main() throws IOException {
		//		IOFast.setFileIO("rle-size.in", "rle-size.out");
		try { run(); }
		catch (EndOfFileRuntimeException e) { }
		io.out.flush();
	}
	public static void main(String[] args) throws IOException { new Main().main(); }
	
	static class EndOfFileRuntimeException extends RuntimeException {
		private static final long serialVersionUID = -8565341110209207657L; }

	static
	public class IOFast {
		private BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		private PrintWriter out = new PrintWriter(System.out);

		void setFileIn(String ins) throws IOException { in.close(); in = new BufferedReader(new FileReader(ins)); }
		void setFileOut(String outs) throws IOException { out.flush(); out.close(); out = new PrintWriter(new FileWriter(outs)); }
		void setFileIO(String ins, String outs) throws IOException { setFileIn(ins); setFileOut(outs); }

		private static int pos, readLen;
		private static final char[] buffer = new char[1024 * 8];
		private static char[] str = new char[500*8*2];
		private static boolean[] isDigit = new boolean[256];
		private static boolean[] isSpace = new boolean[256];
		private static boolean[] isLineSep = new boolean[256];

		static { for(int i = 0; i < 10; i++) { isDigit['0' + i] = true; } isDigit['-'] = true; isSpace[' '] = isSpace['\r'] = isSpace['\n'] = isSpace['\t'] = true; isLineSep['\r'] = isLineSep['\n'] = true; }
		public int read() throws IOException { if(pos >= readLen) { pos = 0; readLen = in.read(buffer); if(readLen <= 0) { throw new EndOfFileRuntimeException(); } } return buffer[pos++]; }
		public int nextInt() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); int i = 0; int ret = 0; if(str[0] == '-') { i = 1; } for(; i < len; i++) ret = ret * 10 + str[i] - '0'; if(str[0] == '-') { ret = -ret; } return ret; }
		public long nextLong() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); int i = 0; long ret = 0; if(str[0] == '-') { i = 1; } for(; i < len; i++) ret = ret * 10 + str[i] - '0'; if(str[0] == '-') { ret = -ret; } return ret; }
		public char nextChar() throws IOException { while(true) { final int c = read(); if(!isSpace[c]) { return (char)c; } } }
		int reads(int len, boolean[] accept) throws IOException { try { while(true) { final int c = read(); if(accept[c]) { break; } if(str.length == len) { char[] rep = new char[str.length * 3 / 2]; System.arraycopy(str, 0, rep, 0, str.length); str = rep; } str[len++] = (char)c; } } catch(EndOfFileRuntimeException e) { ; } return len; }
		int reads(char[] cs, int len, boolean[] accept) throws IOException { try { while(true) { final int c = read(); if(accept[c]) { break; } cs[len++] = (char)c; } } catch(EndOfFileRuntimeException e) { ; } return len; }
		public char[] nextLine() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isLineSep); try { if(str[len-1] == '\r') { len--; read(); } } catch(EndOfFileRuntimeException e) { ; } return Arrays.copyOf(str, len); }
		public String nextString() throws IOException { return new String(next()); }
		public char[] next() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); return Arrays.copyOf(str, len); }
		public int next(char[] cs) throws IOException { int len = 0; cs[len++] = nextChar(); len = reads(cs, len, isSpace); return len; }
		public double nextDouble() throws IOException { return Double.parseDouble(nextString()); }
		public long[] nextLongArray(final int n) throws IOException { final long[] res = new long[n]; for(int i = 0; i < n; i++) { res[i] = nextLong(); } return res; }
		public int[] nextIntArray(final int n) throws IOException { final int[] res = new int[n]; for(int i = 0; i < n; i++) { res[i] = nextInt(); } return res; }
		public int[][] nextIntArray2D(final int n, final int k) throws IOException { final int[][] res = new int[n][]; for(int i = 0; i < n; i++) { res[i] = nextIntArray(k); } return res; }
		public int[][] nextIntArray2DWithIndex(final int n, final int k) throws IOException { final int[][] res = new int[n][k+1]; for(int i = 0; i < n; i++) { for(int j = 0; j < k; j++) { res[i][j] = nextInt(); } res[i][k] = i; } return res; }
		public double[] nextDoubleArray(final int n) throws IOException { final double[] res = new double[n]; for(int i = 0; i < n; i++) { res[i] = nextDouble(); } return res; }
	}
}