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


public class Main
{
	private InputStream is;
	private PrintWriter out;
	int time = 0, freq[], start[], end[], dist[], black[], MOD = (int) (1e9 + 7), arr[], weight[][], x[], y[], parent[];
	int MAX = 1000001, N, K;
	long red[], ans = Long.MAX_VALUE;

	ArrayList<Integer>[] amp;
	ArrayList<Pair>[] pmp;
	boolean b[];
	boolean boo[][], b1[];
	Pair prr[];
	HashMap<Pair, Integer> hm = new HashMap();
	int Dp[][] = new int[1100][1100];

	void soln() 
	{
		is = System.in;
		out = new PrintWriter(System.out);
		long s = System.currentTimeMillis();
		solve();

		// out.close();
		out.flush();
		// tr(System.currentTimeMillis() - s + "ms");
	}

	static class ST1 // min ST
	{
		long arr[], st[];
		int size;

		ST1(long a[]) {
			arr = a.clone();
			size = 10 * arr.length;
			st = new long[size];
			build(0, arr.length - 1, 1);
		}

		void build(int ss, int se, int si) {
			if (ss == se) {
				st[si] = arr[ss];
				return;
			}
			int mid = (ss + se) / 2;
			int val = 2 * si;
			build(ss, mid, val);
			build(mid + 1, se, val + 1);
			st[si] = Math.min(st[val], st[val + 1]);
		}

		void update(int ss, int se, int idx, long val, int si) {
			if (ss == se) {
				// if(si==idx+1)
				st[si] = val;
				return;
			}
			int mid = (ss + se) / 2;
			if (ss <= idx && idx <= mid) {
				update(ss, mid, idx, val, 2 * si);
			} else {
				update(mid + 1, se, idx, val, 2 * si + 1);
			}
			int v = 2 * si;
			st[si] = Math.min(st[v], st[v + 1]);
		}

		long get(int ss, int se, int l, int r, int si) {
			if (l > se || r < ss || l > r)
				return Long.MAX_VALUE / 1000;
			if (l <= ss && r >= se)
				return st[si];
			int mid = (ss + se) / 2;
			int val = 2 * si;
			return Math.min(get(ss, mid, l, r, val), get(mid + 1, se, l, r, val + 1));
		}
	}

	public static void main(String[] args) throws Exception
	{
		new Thread(null, new Runnable() 
		{
			public void run() 
			{
				try 
				{
					// new CODEFORCES().soln();
				} catch (Exception e) 
				{
					System.out.println(e);
				}
			}
		}, "1", 1 << 26).start();
		new Main().soln();
	}

	int D[][];
	char ch[][], ch1[];
	int hash = 29;
	int x2, y2;
	HashSet<Integer>[] hs = (HashSet<Integer>[]) new HashSet[110];
	cell[] c;
	Pair[] p = new Pair[4];
	HashSet<String> set = new HashSet<>();
	HashSet<String> dp = new HashSet<>();
	private void solve()
	{
		int n = ni();
		char ch[] = ns().toCharArray();
		int arr[] = new int[256];
		for(char c : ch) {
			arr[c]++;
		}
		int val = 0;
		for(int i : arr) val += i/2;
		TreeSet<Integer> ts = new TreeSet<>();
		for(int i = 1;i<=n;i++) if(n%i==0) ts.add(i);
		StringBuilder sb = new StringBuilder();
		for(int k : ts){
            int y = n/k;
            int x = k*(y/2);
            if(val >= x){
                ArrayList<Character> amp = new ArrayList<>();
                for(int i = 0; i < 256; i++){
                    if(arr[i] % 2 != 0){
                    	amp.add((char)(i));
                        arr[i]--;
                    }
                }
                int z = val - x;
                z *= 2;
                for(int i = 0; i < 256; i++){
                    while(z > 0 && arr[i] > 0){
                    	amp.add((char)i);
                        arr[i]--;
                        z--;
                    }
                }
                int p = 0, q = 0;
                out.println(k);
                while(k-- > 0){
                    char[] c = new char[y];
                    int r = 0;
                    while(r<y/2){
                        while(arr[q] <= 0) q++;
                        c[r] = (char)(q);
                        c[y-r-1] = (char)(q);
                        arr[q] -= 2;
                        r++;
                    }
                    if(y % 2 != 0){
                        c[r] = amp.get(p++);
                    }
                    sb.append(new String(c)+" ");
                }
                out.println(sb);
                break;
            }
        }
		
	}
	void replace(String str, String prev) {
		if(dp.contains(str)) return;
		dp.add(str);
		if(set.contains(str)) {
			return;
		}
		else {
			boolean b = false;
			str = str.replaceFirst("u","oo");
			if(!str.equals(prev)) {
				replace(str, str);
				b = true;
			}
			str = str.replaceFirst("kh","h");
			if(!str.equals(prev)) {
				replace(str, str);
				b = true;
			}
			if(!b) {
				set.add(str);
				return;
			}
		}
	}
	void bfs(int s, int n) {
		b = new boolean[n];
		dist = new int[n];
		Arrays.fill(dist, 1000000);
		dist[s] = 0;
		b[s] = true;
		Queue<Integer> q = new LinkedList<>();
		q.add(s);
		while(!q.isEmpty()) {
			int y = q.poll();
			for(int i : amp[y]) {
				dist[i] = min(dist[i],dist[y]+1);
				if(!b[i]) {
					b[i] = true;
					q.add(i);
				}
			}
		}
	}
	boolean check(String s, String s1) {
		char ch1[] = s.toCharArray(), ch2[] = s1.toCharArray();
		int arr[] = new int[10];
		for(char c : ch1) {
			arr[c-'0']++;
		}
		int ans = 0;
		for(char c:ch2) {
			arr[c-'0']--;
		}
		
		for(int i:arr) ans += ((i>0)?i:0);
		return ans==3;
	}
	void seive(int n)
	{
		start = new int[n];
		for(int i = 2;i<n;i++) {
			if(start[i]==0) {
				for(int j = 2*i;j<n;j+=i) {
					start[j] = i;
				}
			}
		}
	}
	void print(int[][] arr) 
	{
		int seed = 110, n = arr.length - 220;
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				System.out.print(arr[i + seed][j + seed] + " ");
			}
			System.out.println();
		}
		System.out.println();
	}

	 class cell implements Comparable<cell>
	 {
		int s, d, p, i;

		cell(int t, int d, int p, int i) {
			this.s = t;
			this.p = p;
			this.d = d;
			this.i = i;
		}

		public int compareTo(cell other) {
			// return Integer.compare(val, other.val);
			return Long.compare(d, other.d) != 0 ? (Long.compare(d, other.d)): (Long.compare(i,other.i));
											// other.v));//((Long.compare(u, other.u) != 0 ? (Long.compare(u, other.u)):
											// (Long.compare(v, other.v)))
			// &(Long.compare(u, other.v) != 0 ? (Long.compare(u, other.v)):
			// (Long.compare(v, other.u))));
		}

		public String toString() {
			return this.d + " " + this.s +" "+this.p+" "+this.i;
		}
	}

	int abs(int x)
	{
		return ((x > 0) ? x : -x);
	}

	long ret(int p) 
	{
		if (p >= 0)
			return 0;
		else
			return 1;
	}

	long val(int p, int a, int b) 
	{
		if (p >= 0) {
			return (a * 1l * p);
		}
		return (b * 1l * p);
	}

	void ternary_search(int l, int r) 
	{
		// System.out.println(l+" "+r+" "+ans);
		// for(int i : arr) System.out.print(i+" ");
		// System.out.println();
		if (r >= l) {
			int mid1 = l + (r - l) / 3;
			int mid2 = r - (r - l) / 3;
			long cnt1 = 0, cnt2 = 0;
			cnt1 = compute(mid1);
			cnt2 = compute(mid2);
			// System.out.println(mid1+" "+ cnt1+" "+mid2+" "+cnt2);
			ans = Math.min(cnt1, cnt2);
			if (cnt1 < cnt2) {
				ternary_search(l, mid2 - 1);
			} else {
				ternary_search(mid1 + 1, r);
			}
		}
		return;
	}

	long compute(int x) 
	{
		long ans = 0;
		int c = arr[0];
		for (int i = 1; i <= x; i++) {
			ans += max(c + 1 - arr[i], 0);
			c = max(c + 1, arr[i]);
		}
		int temp = arr[x];
		arr[x] = max(c + 1, arr[x]);
		// SSystem.out.println(arr[x]+" "+ans);
		c = arr[arr.length - 1];
		for (int i = arr.length - 1; i > x; i--) {
			ans += max(c + 1 - arr[i - 1], 0);
			c = max(c + 1, arr[i - 1]);
		}
		arr[x] = temp;
		return ans;
	}

	public int getParent(int x) 
	{
		while (parent[x] != x) {
			parent[x] = parent[parent[x]];
			x = parent[x];
		}
		return x;
	}

	void getFactors(int n, int x)
	{
		for (int i = 1; i * i <= n; i++) {
			if (n % i == 0) {
				hs[x].add(i);
				hs[x].add(n / i);
			}
		}
	}

	void recur(int a, int b, int k) 
	{
		if (k == 0) {
			if (a == x2 && b == y2)
				ans++;
			return;
		}
		recur(a, b + 1, k - 1);
		recur(a, b - 1, k - 1);
		recur(a + 1, b, k - 1);
		recur(a - 1, b, k - 1);
	}

	int min(int a, int b) 
	{
		return (a < b) ? a : b;
	}

	/*private class Cell implements Comparable<Cell> {
		int u, v, s;

		public Cell(int u, int v, int s) {
			this.u = u;
			this.v = v;
			this.s = s;
		}

		public int hashCode() {
			return Objects.hash();
		}

		public int compareTo(Cell other) {
			return (Long.compare(s, other.s) != 0 ? (Long.compare(s, other.s))
					: (Long.compare(v, other.v) != 0 ? Long.compare(v, other.v) : Long.compare(u, other.u)))
					& ((Long.compare(s, other.s) != 0 ? (Long.compare(s, other.s))
							: (Long.compare(u, other.v) != 0 ? Long.compare(u, other.v) : Long.compare(v, other.u))));
		}

		public String toString() {
			return this.u + " " + this.v;
		}
	}*/

	class Pair implements Comparable<Pair>
	{
		int u ,v,i;

		Pair(int u, int v) {
			this.u = u;
			this.i = v;
		}

		Pair(int u, int v, int i) {
			this.u = u;
			this.v = v;
			this.i = i;
		}

		public int hashCode() {
			return Objects.hash();
		}

		public boolean equals(Object o) {
			Pair other = (Pair) o;
			return ((u == other.u && v == other.v));
		}

		public int compareTo(Pair other) {
			// return Integer.compare(val, other.val);
			return Long.compare(u, other.u) != 0 ? (Long.compare(u, other.u)) : (Long.compare(i, other.i));// ((Long.compare(u,
		
		}									
		public String toString() {
			return this.u + " " + this.v +" "+this.i;
		}
	}

	int max(int a, int b) 
	{
		if (a > b)
			return a;
		return b;
	}

	static class FenwickTree 
	{

		int[] array; // 1-indexed array, In this array We save cumulative
						// information to perform efficient range queries and
						// updates

		public FenwickTree(int size) {
			array = new int[size + 1];
		}

		public int rsq(int ind) {
			assert ind > 0;
			int sum = 0;
			while (ind > 0) {
				sum += array[ind];
				// Extracting the portion up to the first significant one of the
				// binary representation of 'ind' and decrementing ind by that
				// number
				ind -= ind & (-ind);
			}
			return sum;
		}

		public int rsq(int a, int b) {
			assert b >= a && a > 0 && b > 0;
			return rsq(b) - rsq(a - 1);
		}

		public void update(int ind, int value) {
			assert ind > 0;
			while (ind < array.length) {
				array[ind] += value;
				// Extracting the portion up to the first significant one of the
				// binary representation of 'ind' and incrementing ind by that
				// number
				ind += ind & (-ind);
			}
		}

		public int size() {
			return array.length - 1;
		}
	}

	void buildGraph(int n)
	{
		for (int i = 0; i < n; i++) {
			int x1 = ni(), y1 = ni(), z = ni();
			//pmp[x1].add(new Pair(y1, z));
		}
	}

	long modInverse(long a, long mOD2)
	{
		return power(a, mOD2 - 2, mOD2);
	}

	long power(long x, long y, long m) 
	{
		if (y == 0)
			return 1;
		long p = power(x, y / 2, m) % m;
		p = (p * p) % m;

		return (y % 2 == 0) ? p : (x * p) % m;
	}

	public long gcd(long a, long b)
	{
		if (b == 0)
			return a;
		return gcd(b, a % b);
	}

	static class ST 
	{
		int arr[], lazy[], n;

		ST(int a) {
			n = a;
			arr = new int[10 * n];
			lazy = new int[10 * n];
		}

		void up(int l, int r, int val) {
			update(0, n - 1, 0, l, r, val);
		}

		void update(int l, int r, int c, int x, int y, int val) {
			if (lazy[c] != 0) {
				lazy[2 * c + 1] += lazy[c];
				lazy[2 * c + 2] += lazy[c];
				if (l == r)
					arr[c] += lazy[c];
				lazy[c] = 0;
			}
			if (l > r || x > y || l > y || x > r)
				return;
			if (x <= l && y >= r)

			{
				lazy[c] += val;
				return;
			}
			int mid = l + r >> 1;
			update(l, mid, 2 * c + 1, x, y, val);
			update(mid + 1, r, 2 * c + 2, x, y, val);
			arr[c] = Math.max(arr[2 * c + 1], arr[2 * c + 2]);
		}

		int an(int ind) {
			return ans(0, n - 1, 0, ind);
		}

		int ans(int l, int r, int c, int ind) {
			if (lazy[c] != 0) {
				lazy[2 * c + 1] += lazy[c];
				lazy[2 * c + 2] += lazy[c];
				if (l == r)
					arr[c] += lazy[c];
				lazy[c] = 0;
			}
			if (l == r)
				return arr[c];
			int mid = l + r >> 1;
			if (mid >= ind)
				return ans(l, mid, 2 * c + 1, ind);
			return ans(mid + 1, r, 2 * c + 2, ind);
		}
	}

	public static int[] shuffle(int[] a, Random gen)
	{
		for (int i = 0, n = a.length; i < n; i++) {
			int ind = gen.nextInt(n - i) + i;
			int d = a[i];
			a[i] = a[ind];
			a[ind] = d;
		}
		return a;
	}

	long power(long x, long y, int mod)
	{
		long ans = 1;
		while (y > 0) {
			if (y % 2 == 0) {
				x = (x * x) % mod;
				y /= 2;
			} else {
				ans = (x * ans) % mod;
				y--;
			}
		}
		return ans;
	}

	// To Get Input
	// Some Buffer Methods
	private byte[] inbuf = new byte[1024];
	public int lenbuf = 0, ptrbuf = 0;

	private int readByte() 
	{
		if (lenbuf == -1)
			throw new InputMismatchException();
		if (ptrbuf >= lenbuf) {
			ptrbuf = 0;
			try {
				lenbuf = is.read(inbuf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (lenbuf <= 0)
				return -1;
		}
		return inbuf[ptrbuf++];
	}

	private boolean isSpaceChar(int c) {
		return !(c >= 33 && c <= 126);
	}

	private int skip() {
		int b;
		while ((b = readByte()) != -1 && isSpaceChar(b))
			;
		return b;
	}

	private double nd() {
		return Double.parseDouble(ns());
	}

	private char nc() {
		return (char) skip();
	}

	private String ns() {
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != '
									// ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	private char[] ns(int n) {
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while (p < n && !(isSpaceChar(b))) {
			buf[p++] = (char) b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}

	private char[][] nm(int n, int m) {
		char[][] map = new char[n][];
		for (int i = 0; i < n; i++)
			map[i] = ns(m);
		return map;
	}

	private int[] na(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = ni();
		return a;
	}

	private int ni() {
		int num = 0, b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	private long nl() {
		long num = 0;
		int b;
		boolean minus = false;
		while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
			;
		if (b == '-') {
			minus = true;
			b = readByte();
		}

		while (true) {
			if (b >= '0' && b <= '9') {
				num = num * 10 + (b - '0');
			} else {
				return minus ? -num : num;
			}
			b = readByte();
		}
	}

	private boolean oj = System.getProperty("ONLINE_JUDGE") != null;

	private void tr(Object... o) {
		if (!oj)
			System.out.println(Arrays.deepToString(o));
	}
}