Problem: You are given n k-digit integers. You have to rearrange the digits in the integers so that the difference between the largest and the smallest number was minimum. Digits should be rearranged by the same rule in all integers.

Input

The first line contains integers n and k — the number and digit capacity of numbers correspondingly (1 ≤ n, k ≤ 8). Next n lines contain k-digit positive integers. Leading zeroes are allowed both in the initial integers and the integers resulting from the rearranging of digits.

Output

Print a single number: the minimally possible difference between the largest and the smallest number after the digits are rearranged in all integers by the same rule.

Examples

Input

6 4
5237
2753
7523
5723
5327
2537


Output

2700


Input

3 3
010
909
012


Output

3


Input

7 5
50808
36603
37198
44911
29994
42543
50156


Output

20522

Note

In the first sample, if we rearrange the digits in numbers as (3,1,4,2), then the 2-nd and the 4-th numbers will equal 5237 and 2537 correspondingly (they will be maximum and minimum for such order of digits).

In the second sample, if we swap the second digits and the first ones, we get integers 100, 99 and 102.

Solution (in JAVA):

Solution:
//package clipse;


import java.util.*;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;
import java.io.*;
import java.math.*;


public class AA
{
	
	static StringBuilder sb;
	
	static dsu dsu;
	
	
	
	
	static int[] swap(int data[], int left, int right)
    {
  
        // Swap the data
        int temp = data[left];
        data[left] = data[right];
        data[right] = temp;
  
        // Return the updated array
        return data;
    }
  
    // Function to reverse the sub-array
    // starting from left to the right
    // both inclusive
     static int[] reverse(int data[], int left, int right)
    {
  
        // Reverse the sub-array
        while (left < right) {
            int temp = data[left];
            data[left++] = data[right];
            data[right--] = temp;
        }
  
        // Return the updated array
        return data;
    }
  
    // Function to find the next permutation
    // of the given integer array
    public static boolean findNextPermutation(int data[])
    {
  
        // If the given dataset is empty
        // or contains only one element
        // next_permutation is not possible
        if (data.length <= 1)
            return false;
  
        int last = data.length - 2;
  
        // find the longest non-increasing suffix
        // and find the pivot
        while (last >= 0) {
            if (data[last] < data[last + 1]) {
                break;
            }
            last--;
        }
  
        // If there is no increasing pair
        // there is no higher order permutation
        if (last < 0)
            return false;
  
        int nextGreater = data.length - 1;
  
        // Find the rightmost successor to the pivot
        for (int i = data.length - 1; i > last; i--) {
            if (data[i] > data[last]) {
                nextGreater = i;
                break;
            }
        }
  
        // Swap the successor and the pivot
        data = swap(data, nextGreater, last);
  
        // Reverse the suffix
        data = reverse(data, last + 1, data.length - 1);
  
        // Return true as the next_permutation is done
        return true;
    }
  
	
	
	
	
	
	
	
	
	static void solve()
    {
		int n=i();
		int k=i();
		int A[][]=new int[n][k];
		char c[][]=new char[n][k];
		for(int i=0;i<n;i++)
		{
			c[i]=s().toCharArray();
			for(int j=0;j<k;j++)
			{
				A[i][j]=c[i][j]-'0';
			}
			
			
		}
		
		int per[]=new int[k];
		for(int i=0;i<k;i++)
			per[i]=i;
		
		int ans=Integer.MAX_VALUE;
		do {
			int min=Integer.MAX_VALUE;
			int max=Integer.MIN_VALUE;
			for(int i=0;i<n;i++)
			{
				int c1=0;
				for(int j=0;j<k;j++)
				{
					c1=(10*c1)+A[i][per[j]];
				}
				min=Math.min(min,c1);

				max=Math.max(max,c1);
				
			}
			ans=Math.min(ans,Math.abs(min-max));	
		}while(findNextPermutation(per)!=false);
		System.out.println(ans);
		
		
		
		
		
		
		
		
		
		
		
		
    }
		
				

	
			
			
			
			
		
		
		
		
		
		
    
	
	
	

	
	
	
	
	
	 public static void main(String[] args)
	 {
		
	         sb=new StringBuilder();
	        int test=1;
	        while(test-->0) 
	        {
	        	
	    		
	        	 solve();
	        }
	        
	         System.out.println(sb);
	         
	         
	         
	    }
	 
	 //*********************************Disjoint set union*************************//
	 static class dsu
	 {
		 int parent[];
		 dsu(int n)
		 {
			 parent=new int[n];
			 for(int i=0;i<n;i++)
				 parent[i]=-1;
		 }
		 int find(int a)
		 {
			 if(parent[a]<0)
				 return a;
			 else
			 {
				 int x=find(parent[a]);
				 parent[a]=x;
				 return x;
			 }
		 }
		 void merge(int a,int b)
		 {
			 a=find(a);
			 b=find(b);
			 if(a==b)
				 return;
			 parent[b]=a;
		 }
	 }
	 
	 
	 
//*******************************************PRIME FACTORIZE *****************************************************************************************************//
	 static TreeMap<Integer,Integer> prime(long n)
	 {
		 TreeMap<Integer,Integer>h=new TreeMap<>();
		 long num=n;
		 for(int i=2;i<=Math.sqrt(num);i++)
		 {
			 if(n%i==0)
			 {
				 int nt=0;
				 while(n%i==0) {
					 n=n/i;
					 nt++;
				 }
				 h.put(i, nt);
			 }
		 }
		 if(n!=1)
			 h.put((int)n, 1);
		 return h;
		 
	 }
	 
	
	
//*************CLASS PAIR ***********************************************************************************************************************************************
	    static class pair implements Comparable<pair>
	    {
	        int x;
	        int y;

	        pair(int x, int y) {
	            this.x = x;
	            this.y = y;
	        }
	        public int compareTo(pair o)
	        {
	        	return x-o.x==0?y-o.y:x-o.x;
	        	
	        }
			
	       
	    }
//*************CLASS PAIR *****************************************************************************************************************************************************
	
	
	

    static 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);
        }
    }

    static 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();
        }
    }

    static InputReader in = new InputReader(System.in);
    static OutputWriter out = new OutputWriter(System.out);
   

    public static int[] sort(int[] a) {
        int n = a.length;
        ArrayList<Integer> l = new ArrayList<>();
        for (int i : a)
            l.add(i);
        Collections.sort(l);
        for (int i = 0; i < l.size(); i++)
            a[i] = l.get(i);
        return a;
    }

    public static long pow(long x, long y) {
        long res = 1;
        while (y > 0) {
            if (y % 2 != 0) {
                res = (res * x);// % modulus;
                y--;

            }
            x = (x * x);// % modulus;
            y = y / 2;
        }
        return res;
    }
//GCD___+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    public static long gcd(long x, long y) {
        if (x == 0)
            return y;
        else
            return gcd(y % x, x);
    }
    //****************LOWEST COMMON MULTIPLE   *************************************************************************************************************************************

    public static long lcm(long x, long y) {
        return (x * (y / gcd(x, y)));
    }
//INPUT PATTERN******************************************************************************************************************************************************************
    public static int i() {
        return in.Int();
    }

    public static long l() {
        String s = in.String();
        return Long.parseLong(s);
    }

    public static String s() {
        return in.String();
    }

    public static int[] readArray(int n) {
        int A[] = new int[n];
        for (int i = 0; i < n; i++) {
            A[i] = i();
        }
        return A;
    }

    public static long[] readArray(long n) {
        long A[] = new long[(int) n];
        for (int i = 0; i < n; i++) {
            A[i] = l();
        }
        return A;
    }

}