Arkady invited Anna for a dinner to a sushi restaurant. The restaurant is a bit unusual: it offers n pieces of sushi aligned in a row, and a customer has to choose a continuous subsegment of these sushi to buy.

The pieces of sushi are of two types: either with tuna or with eel. Let's denote the type of the i-th from the left sushi as t_i, where t_i = 1 means it is with tuna, and t_i = 2 means it is with eel.

Arkady does not like tuna, Anna does not like eel. Arkady wants to choose such a continuous subsegment of sushi that it has equal number of sushi of each type and each half of the subsegment has only sushi of one type. For example, subsegment [2, 2, 2, 1, 1, 1] is valid, but subsegment [1, 2, 1, 2, 1, 2] is not, because both halves contain both types of sushi.

Find the length of the longest continuous subsegment of sushi Arkady can buy.

Input

The first line contains a single integer n (2 ≤ n ≤ 100 000) — the number of pieces of sushi.

The second line contains n integers t_1, t_2, ..., t_n (t_i = 1, denoting a sushi with tuna or t_i = 2, denoting a sushi with eel), representing the types of sushi from left to right.

It is guaranteed that there is at least one piece of sushi of each type. Note that it means that there is at least one valid continuous segment.

Output

Print a single integer — the maximum length of a valid continuous segment.

Examples

Input


7
2 2 2 1 1 2 2


Output


4


Input


6
1 2 1 2 1 2


Output


2


Input


9
2 2 1 1 1 2 2 2 2


Output


6

Note

In the first example Arkady can choose the subsegment [2, 2, 1, 1] or the subsegment [1, 1, 2, 2] with length 4.

In the second example there is no way but to choose one of the subsegments [2, 1] or [1, 2] with length 2.

In the third example Arkady's best choice is the subsegment [1, 1, 1, 2, 2, 2].
	import java.io.BufferedWriter;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.io.OutputStreamWriter;
	import java.io.PrintWriter;
	import java.io.Writer;
	import java.util.Arrays;
	import java.util.InputMismatchException;
	import java.util.*;
	import java.io.*;
	import java.math.*;
	public class Main5{

	static class Pair
		{ 
			int x; 
			int y;
			public Pair(int x, int y) 
			{	 
				this.x = x; 
				this.y = y; 
			}	 
		} 
		static class Compare
		{ 
			static void compare(Pair arr[], int n) 
			{ 
				// Comparator to sort the pair according to second element 
				Arrays.sort(arr, new Comparator<Pair>() { 
					@Override public int compare(Pair p1, Pair p2) 
					{ 
						if(p1.x>p2.x)
						{
							return 1;
						}
						else if(p2.x>p1.x)
						{
							return -1;
						}
						else
						{
							return 0;
						} 
					} 
				}); 
			} 
		}
		public static long pow(long a, long b)
		{
			long result=1;
			while(b>0)
			{
				if (b % 2 != 0)
				{
					result=(result*a)%mod;
					b--;
				} 
				a=(a*a)%mod;
				b /= 2;
			}   
			return result;
		}
		public static long fact(long num)
		{
					long value=1;
					int i=0;
					for(i=2;i<num;i++)
					{
						value=((value%mod)*i%mod)%mod;
					}
					return value;
				}
				public static long gcd(long a, long b)
				{
					if (a == 0)
						return b;
					return gcd(b%a, a);
				}
				
				public static long lcm(int a,int b)
				{
					return a * (b / gcd(a, b));
				}
				public static long sum(int h)
				{
					return (h*(h+1)/2);
				}
				public static int[] sort(int[] a)
				{
					int n=a.length;
					ArrayList<Integer> arr=new ArrayList<Integer>();
					for(int i=0;i<n;i++)
					{
						arr.add(a[i]);
					}
					Collections.sort(arr);
					for(int i=0;i<arr.size();i++)
					{
						a[i]=arr.get(i);
					}
					return a;
				}
				public static void dfs(int parent,boolean[] visited)
				{
					ArrayList<Integer> arr=new ArrayList<Integer>();
					arr=graph.get(parent);
					visited[parent]=true;
					for(int i=0;i<arr.size();i++)
					{
						int num=arr.get(i);
						if(visited[num]==false)
						{
							dfs(num,visited);
						}
					//	bache[parent]+=bache[num]+1;
					}
					
				}
				static int[] dis;
				static ArrayList<Integer> ar3;
				static long mod=1000000007L;
				static ArrayList<ArrayList<Integer>> graph;
				public static void bfs(int num,boolean[] visited)
				{
					Queue<Integer> q=new LinkedList<>();
					q.add(num);
					dis[num]=0;
					visited[num]=true;
					while(!q.isEmpty())
					{
						int x=q.poll();
						ArrayList<Integer> al=graph.get(x);
						for(int i=0;i<al.size();i++)
						{
							int y=al.get(i);
							if(visited[y]==false)
							{
								q.add(y);
								dis[y]=dis[x]+1;
								visited[y]=true;
							}
						}
					}
				}
							  
		
				
				public static void main(String args[])throws IOException
				{
				//	InputReader in=new InputReader(System.in);
				//	OutputWriter out=new OutputWriter(System.out);
				//	long a=pow(26,1000000005);
				    BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
					ArrayList<Integer> ar=new ArrayList<>();
				//	ArrayList<Integer> index=new ArrayList<>();
					ArrayList<Integer> ar2=new ArrayList<>();
			//		ArrayList<Integer> ar3=new ArrayList<>();
					ArrayList<Integer> ar4=new ArrayList<>();
					TreeSet<Integer> ts=new TreeSet<>();
				//	TreeSet<String> pre=new TreeSet<>();
					HashMap<Integer,Integer> hash=new HashMap<>();
					HashMap<Integer,Integer> hash1=new HashMap<Integer,Integer>();
					HashMap<Long,Integer> hash2=new HashMap<Long,Integer>();
			/*		boolean[] prime=new boolean[1000001];
					for(int i=2;i*i<=1000000;i++)
					{
						if(prime[i]==false)
						{
							for(int j=2*i;j<=1000000;j+=i)
							{
								prime[j]=true;
								
							}
							//389378484
						}
					}*/
					int n=i();
					int[] a=new int[n];
					int count=0,count1=0;
					for(int i=0;i<n;i++)
					{
						a[i]=i();
						if(a[i]==1)
						{
							if(count1!=0)
							{
								ar.add(count1);
							}
							count1=0;
							count++;
						}
						if(a[i]==2)
						{
							if(count!=0)
							{
								ar.add(count);
							}
							count=0;
							count1++;
						}
					}
					if(count!=0)
					{
						ar.add(count);
					}
					if(count1!=0)
					{
						ar.add(count1);
					}
					int min=0;
			//		pln(ar+"");
					for(int i=0;i<ar.size()-1;i++)
					{
						int ans=Math.min(ar.get(i),ar.get(i+1));
						min=Math.max(ans,min);
					}
					pln(min*2+"");
				}
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				
				/**/
				static InputReader in=new InputReader(System.in);
					static OutputWriter out=new OutputWriter(System.out);
					public static long l()
					{
						String s=in.String();
						return Long.parseLong(s);
					}
					public static void pln(String value)
					{
						System.out.println(value);
					}
					public static int i()
					{
						return in.Int();
					}
					public static String s()
					{
						return in.String();
					}
		}
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			 
			class InputReader {
				 
				private InputStream stream;
				private byte[] buf = new byte[1024];
				private int curChar;
				private int numChars;
				private SpaceCharFilter filter;
			 
				public InputReader(InputStream stream) {
					this.stream = stream;
				}
			 
				public int read() {
					if (numChars== -1)
						throw new InputMismatchException();
					if (curChar >= numChars) {
						curChar = 0;
						try {
							numChars = stream.read(buf);
						} catch (IOException e) {
							throw new InputMismatchException();
						}
						if (numChars <= 0)
							return -1;
					}
					return buf[curChar++];
				}
			 
				public int Int() {
					int c = read();
					while (isSpaceChar(c))
						c = read();
					int sgn = 1;
					if (c == '-') {
						sgn = -1;
						c = read();
					}
					int res = 0;
					do {
						if (c < '0' || c > '9')
							throw new InputMismatchException();
						res *= 10;
						res += c - '0';
						c = read();
					} while (!isSpaceChar(c));
					return res * sgn;
				}
			 
				public String String() {
					int c = read();
					while (isSpaceChar(c))
						c = read();
					StringBuilder res = new StringBuilder();
					do {
						res.appendCodePoint(c);
						c = read();
					} while (!isSpaceChar(c));
					return res.toString();
				}
			 
				public boolean isSpaceChar(int c) {
					if (filter != null)
						return filter.isSpaceChar(c);
					return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
				}
			 
				public String next() {
					return String();
				}
			 
				public interface SpaceCharFilter {
					public boolean isSpaceChar(int ch);
				}
			}
			 
			class OutputWriter {
				private final PrintWriter writer;
			 
				public OutputWriter(OutputStream outputStream) {
					writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
				}
			 
				public OutputWriter(Writer writer) {
					this.writer = new PrintWriter(writer);
				}
			 
				public void print(Object...objects) {
					for (int i = 0; i < objects.length; i++) {
						if (i != 0)
							writer.print(' ');
						writer.print(objects[i]);
					}
				}
			 
				public void printLine(Object...objects) {
					print(objects);
					writer.println();
				}
			 
				public void close() {
					writer.close();
				}
			 
				public void flush() {
					writer.flush();
				}
			 
				}
			 
				class IOUtils {
			 
				public static int[] readIntArray(InputReader in, int size) {
					int[] array = new int[size];
					for (int i = 0; i < size; i++)
						array[i] = in.Int();
					return array;
				}
			 
				} 