Problem: Kolya has a string s of length n consisting of lowercase and uppercase Latin letters and digits.

He wants to rearrange the symbols in s and cut it into the minimum number of parts so that each part is a palindrome and all parts have the same lengths. A palindrome is a string which reads the same backward as forward, such as madam or racecar.

Your task is to help Kolya and determine the minimum number of palindromes of equal lengths to cut s into, if it is allowed to rearrange letters in s before cuttings.

Input

The first line contains an integer n (1 ≤ n ≤ 4·105) — the length of string s.

The second line contains a string s of length n consisting of lowercase and uppercase Latin letters and digits.

Output

Print to the first line an integer k — minimum number of palindromes into which you can cut a given string.

Print to the second line k strings — the palindromes themselves. Separate them by a space. You are allowed to print palindromes in arbitrary order. All of them should have the same length.

Examples

Input

6
aabaac


Output

2
aba aca 

Input

8
0rTrT022


Output

1
02TrrT20 

Input

2
aA


Output

2
a A 

Solution (in JAVA):

Solution:
import java.util.*;
import java.io.*;

public class ProblemH
{

    static int mod = (int) (1e9+7);
    static InputReader in;
    static PrintWriter out;
    
    public static void main(String[] args)
    {
        in = new InputReader(System.in);
        out = new PrintWriter(System.out);            

        int n = in.nextInt();
        String s = in.readString();
        int[] cnt = new int[256];
        
        for(int i = 0; i < n; i++)
            cnt[s.charAt(i)]++;
        
        ArrayList<Integer> list = new ArrayList<>();
        for(int i = 1; i <= Math.sqrt(n); i++){
            if(n % i == 0){
                list.add(i);
                if(i * i != n)
                    list.add(n / i);
            }
        }
        Collections.sort(list);
        int lol = 0;
        
        for(int i = 0; i < 256; i++){
            lol += cnt[i] / 2;
        }
        
        for(int k : list){
            int y = n / k;
            int x = k * (y / 2);
            if(lol >= x){
                out.println(k);
                ArrayList<Character> l1 = new ArrayList<>();
                for(int i = 0; i < 256; i++){
                    if(cnt[i] % 2 != 0){
                        l1.add((char)(i));
                        cnt[i]--;
                    }
                }
                int z = lol - x;
                z *= 2;
                for(int i = 0; i < 256; i++){
                    while(z > 0 && cnt[i] > 0){
                        l1.add((char)i);
                        cnt[i]--;
                        z--;
                    }
                }
                int p = 0;
                int q = 0;
                while(k-- > 0){
                    char[] c = new char[y];
                    int r = 0;
                    while(r < y / 2){
                        while(cnt[q] <= 0) q++;
                        c[r] = (char)(q);
                        c[y - r - 1] = (char)(q);
                        cnt[q] -= 2;
                        r++;
                    }
                    if(y % 2 != 0){
                        c[r] = l1.get(p++);
                    }
                    out.print(new String(c) + " ");
                }
                out.println();
                break;
            }
        }
        
        out.close();

    }


    static void debug(Object... o)
    {
            System.out.println(Arrays.deepToString(o));
    }

    static class Pair implements Comparable<Pair>
    {

        int x,y;
        
        
        Pair (int x,int y)
        {
		this.x = x;
                this.y = y;
	}
        
	public int compareTo(Pair o)
        {
            return Integer.compare(this.x,o.x);
		//return 0;
	}

        public boolean equals(Object o)
        {
            if (o instanceof Pair)
            {
                Pair p = (Pair)o;
                return p.x == x && p.y==y;
            }
            return false;
        }

        @Override
        public String toString()
        {
            return x + " "+ y;
        }
        
        public int hashCode()
        {
            return new Long(x).hashCode() * 31 + new Long(y).hashCode();
        }
    
    } 

    static long gcd(long x,long y)
    {
        if(y==0)
                return x;
        else
                return gcd(y,x%y);
    }

    static int gcd(int x,int y)
    {
        if(y==0)
                return x;
        else 
                return gcd(y,x%y);
    }

    static long pow(long n,long p,long m)
    {
         long  result = 1;
          if(p==0)
            return 1;

        while(p!=0)
        {
            if(p%2==1)
                result *= n;
            if(result>=m)
            result%=m;
            p >>=1;
            n*=n;
            if(n>=m)
            n%=m;
        }
        return result;
    }

    static long pow(long n,long p)
    {
        long  result = 1;
          if(p==0)
            return 1;

        while(p!=0)
        {
            if(p%2==1)
                result *= n;	    
            p >>=1;
            n*=n;	    
        }
        return result;
    }

    static class InputReader
    {

        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;
        private SpaceCharFilter filter;

        public InputReader(InputStream stream)
        {
                this.stream = stream;
        }

        public int snext()
        {
                if (snumChars == -1)
                        throw new InputMismatchException();
                if (curChar >= snumChars)
                {
                        curChar = 0;
                        try
                        {
                                snumChars = stream.read(buf);
                        } catch (IOException e)
                        {
                                throw new InputMismatchException();
                        }
                        if (snumChars <= 0)
                                return -1;
                }
                return buf[curChar++];
        }

        public int nextInt()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                int sgn = 1;
                if (c == '-')
                {
                        sgn = -1;
                        c = snext();
                }
                int res = 0;
                do
                {
                        if (c < '0' || c > '9')
                                throw new InputMismatchException();
                        res *= 10;
                        res += c - '0';
                        c = snext();
                } while (!isSpaceChar(c));
                return res * sgn;
        }

        public long nextLong()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                int sgn = 1;
                if (c == '-')
                {
                        sgn = -1;
                        c = snext();
                }
                long res = 0;
                do
                {
                        if (c < '0' || c > '9')
                                throw new InputMismatchException();
                        res *= 10;
                        res += c - '0';
                        c = snext();
                } while (!isSpaceChar(c));
                return res * sgn;
        }

        public int[] nextIntArray(int n)
        {
                int a[] = new int[n];
                for (int i = 0; i < n; i++)
                {
                        a[i] = nextInt();
                }
                return a;
        }

        public long[] nextLongArray(int n)
        {
                long a[] = new long[n];
                for (int i = 0; i < n; i++)
                {
                        a[i] = nextLong();
                }
                return a;
        }

        public String readString()
        {
                int c = snext();
                while (isSpaceChar(c))
                {
                        c = snext();
                }
                StringBuilder res = new StringBuilder();
                do
                {
                        res.appendCodePoint(c);
                        c = snext();
                } while (!isSpaceChar(c));
                return res.toString();
        }

        public String nextLine()
        {
                int c = snext();
                while (isSpaceChar(c))
                        c = snext();
                StringBuilder res = new StringBuilder();
                do
                {
                        res.appendCodePoint(c);
                        c = snext();
                } while (!isEndOfLine(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;
        }

        private boolean isEndOfLine(int c)
        {
                return c == '\n' || c == '\r' || c == -1;
        }

        public interface SpaceCharFilter
        {
                public boolean isSpaceChar(int ch);
        }

    }
}