One day little Vasya found mom's pocket book. The book had n names of her friends and unusually enough, each name was exactly m letters long. Let's number the names from 1 to n in the order in which they are written.

As mom wasn't home, Vasya decided to play with names: he chose three integers i, j, k (1 ≤ i < j ≤ n, 1 ≤ k ≤ m), then he took names number i and j and swapped their prefixes of length k. For example, if we take names "CBDAD" and "AABRD" and swap their prefixes with the length of 3, the result will be names "AABAD" and "CBDRD".

You wonder how many different names Vasya can write instead of name number 1, if Vasya is allowed to perform any number of the described actions. As Vasya performs each action, he chooses numbers i, j, k independently from the previous moves and his choice is based entirely on his will. The sought number can be very large, so you should only find it modulo 1000000007 (109 + 7).

Input

The first input line contains two integers n and m (1 ≤ n, m ≤ 100) — the number of names and the length of each name, correspondingly. Then n lines contain names, each name consists of exactly m uppercase Latin letters.

Output

Print the single number — the number of different names that could end up in position number 1 in the pocket book after the applying the procedures described above. Print the number modulo 1000000007 (109 + 7).

Examples

Input

2 3
AAB
BAA


Output

4


Input

4 5
ABABA
BCGDG
AAAAA
YABSA


Output

216

Note

In the first sample Vasya can get the following names in the position number 1: "AAB", "AAA", "BAA" and "BAB".

import java.io.*;
import java.text.DecimalFormat;
import java.util.*;
public class Template {
	//static int cnt=0;
static Scanner sc=new Scanner(System.in);
	static ArrayList<Long> v=new ArrayList();;
	static int max=1;
	static ArrayList<Integer>[] pair;
	static boolean[] dn;
	static long[] arr;
    static	ArrayList<Long> mLang=new ArrayList();
    static ArrayList<Long> indx;
	static String f3="";
	static Map<Long,Long> s_lcnt=new HashMap();
	static BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); 
	
	public static void main (String[] args) throws java.lang.Exception{
int n=sc.nextInt();
int m=sc.nextInt();
sc.nextLine();
Map<Character,Integer>[] valK=new Map[m];
for(int i=0;i<n;i++) {
	char[] s=sc.nextLine().toCharArray();
	for(int j=0;j<m;j++) {
if(	valK[j]==null) {
	valK[j]=new HashMap();
valK[j].put(s[j], 0);
}
else if( !valK[j].containsKey(s[j])){
	//valK[j]=new HashMap();
	valK[j].put(s[j], 0);
}
	}
}
long ans=1;
for(int i=0;i<m;i++) {
	if(valK[i]!=null) {
	ans*=(long)valK[i].size()%(1000000007);
	ans=ans%1000000007;
	//System.out.println(ans+" "+valK[i].size());
	}
}
System.out.println(ans);

	}
	
	
	
	
	
	
	
	
	public static long fact(long i) {
	long fact=1;
		for(int j=2;j<=i;j++) {
			fact=fact*j;
		}
		return fact;
	}
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	public static void printArrInt(ArrayList<Integer> arr) {
		for(int i=0;i<arr.size();i++) {
			System.out.print(arr.get(i)+" ");
	}	
		}
	
	public static int[][] matrixInp(int n,int m) {
		int[][] arr=new int[n][m];
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				arr[i][j]=sc.nextInt();
			}
		}
		return arr;
	}
	
	
	
	
	
	
	public static int bSearch(ArrayList<Long> arr,long n) {
		
		int start=0;
		int end=arr.size()-1;
		int mid=0;
		while(end>=start) {
		mid=start+(end-start)/2;
		if(arr.get(mid)==n) {
			break;
			
		}
		else if(arr.get(mid)>n) {
			end=mid-1;
		}
		else if(arr.get(mid)<n) {
			start=mid+1;
		}
		}
		return mid;
	}
	

	
	public static int reduceFraction(int a, int b)
	{
		int aa=a;
		if(a==0 || b==0)
			return Math.max(a, b);
		else {
			for(int i=2;i<=Math.min(a, b);i++) {
				if(a%i==0 && b%i==0) {
					a=a/i;
					b=b/i;
					i--;
				}
			}
			
			
		}
		
		return aa/a;
	}
	
	public static long sumDigits(long x) {
		String s=String.valueOf(x);
		//System.out.println(s+" "+sx+" "+x);
		long sum=0;
		for(int i=0;i<s.length();i++) {
			sum+=Long.parseLong(s.substring(i,i+1));
		}
		return sum;
	}
	
	
	public static int[] primeFactofNumb(int num) {
		int[] factors=new int[num+1];
		for(int j=2;j<=Math.sqrt(num);j++) {
			if(num%j==0) {
				factors[j]++;
			}
			while(num%j==0) {
				num=num/j;
			}
			
		}
		
		if(num>1)
			factors[num]++;
		return factors;
	}
	
	
	
	
	public static long nCr(int n, int k){ 
		long C[][] = new long[n + 1][k + 1];
        long i, j;
 
        // Calculate  value of Binomial
        // Coefficient in bottom up manner
        for (i = 0; i <= n; i++) {
            for (j = 0; j <= (long)Math.min(i, k); j++) {
                // Base Cases
                if (j == 0 || j == i)
                    C[(int) i][(int) j] = 1;
 
                // Calculate value using
                // previously stored values
                else
                    C[(int) i][(int) j] = C[(int) (i - 1)][(int) (j - 1)] + C[(int) (i - 1)][(int) j];
            }
        }
 
        return C[n][k];
	}
		
	
		
	

	
	
	

		
	
	
	
	
static long gcd(long a,long b) {
		
	
		if(b==0) {
		return a;
		}
		else if(a==0)
			return b;
			
		
	return gcd(b,a%b);
	
	}
	
	
	
	
	
	public static int s2i(String s) {
		return Integer.parseInt(s);
	}
	

	
	
	public static int LeastIntFn(int a,int b) {
		if((b%a)==0) {
			return (int)b/a;
		}
		return (int)(b/a)+1;
	}
	
	
	
	public static ArrayList<Long> arrInpLong(long n){
		ArrayList<Long> arr=new ArrayList();
		for(long i=0;i<n;i++) {
		arr.add(sc.nextLong());	
		}
		return arr;
	}
	public static ArrayList<String> arrInpStr(int n){
		ArrayList<String> arr=new ArrayList();
		for(int i=0;i<n;i++) {
					arr.add(sc.nextLine());	
		}
		return arr;
	}
	
	public static ArrayList<Integer> arrInpInt(int n){
		ArrayList<Integer> arr=new ArrayList();
		for(int i=0;i<n;i++) {
			int k=sc.nextInt();
			if(k>max)
				max=k;
		arr.add(k);	
		}
		return arr;
	}
	
	

	
	
	public static int min(int a,int b,int c) {
		int min1=Math.min(a, b);
		return Math.min(min1,c);
	}
}