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".
//    A Computer is Like a mischievous genie.
//    It will give you exactly what you ask for,
//    but not always what you want
//    A code by Rahul Verma


import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Set;
import java.util.SortedSet;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;
import javax.swing.plaf.basic.BasicScrollPaneUI.HSBChangeListener;


public class Main {


    static class Clock {

        protected long start, stop;

        public void start() {
            start = System.currentTimeMillis();
        }

        public void stop() {
            stop = System.currentTimeMillis();
        }

        public String getTime() {
            return ((stop - start) + " ms");
        }
    }


    public static PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));

    static class FastReader {

        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String[] nextSArray() {
            String sr[] = null;
            try {
                sr = br.readLine().trim().split(" ");
            } catch (IOException e) {
                e.printStackTrace();
            }
            return sr;
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }

            return str;
        }
    }


    static long powmodulo(long a, long p) {
        if (p == 0) {
            return 1 % mod;
        }
        if (p == 1) {
            return a % mod;
        }
        long ans = 1;
        while (p > 0) {
            if ((p & 1) > 0) {
                ans = (ans * a) % mod;
            }
            a = (a * a) % mod;
            p = p >> 1;
        }
        return ans % mod;
    }


    static long mod = 1000000007;

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

    static long fast_powerNumbers(long a, long n) {
        if (n == 1) {
            return a;
        }
        long ans = fast_powerNumbers(a, n / 2);
        if (n % 2 == 0) {
            return (ans * ans);
        } else {
            return ((ans * ans) * (a));
        }
    }


    static void dfs_helper(int[][] arr, int i, int j, int team, int n, int m) {
        arr[i][j] = team;
        if (i - 1 >= 0 && arr[i - 1][j] == 1) {
            dfs(arr, i - 1, j, team, n, m);
        }
        if (j - 1 >= 0 && arr[i][j - 1] == 1) {
            dfs(arr, i, j - 1, team, n, m);
        }
        if (i + 1 < n && arr[i + 1][j] == 1) {
            dfs(arr, i + 1, j, team, n, m);
        }
        if (j + 1 < m && arr[i][j + 1] == 1) {
            dfs(arr, i, j + 1, team, n, m);
        }

    }

    static void dfs(int[][] arr, int i, int j, int team, int n, int m) {
        dfs_helper(arr, i, j, team, n, m);

    }

    static int parent[];
    static int rank[];

    static int find(int i) {
        if (parent[i] == -1) {
            parent[i] = i;
            return i;
        }

        if (parent[i] == i) {
            return i;
        } else {
            parent[i] = find(parent[i]);
        }
        return parent[i];

    }

    static void unite(int s1, int s2) {

        if (rank[s1] > rank[s2]) {
            parent[s2] = s1;
            rank[s1] += rank[s2];
        } else {
            parent[s1] = s2;
            rank[s2] += rank[s1];
        }
    }


    static int arr[];

    static void seive(int n) {
        arr = new int[n + 1];
        arr[0] = arr[1] = 1;
        for (int i = 4; i <= n; i = i + 2) {
            arr[i] = 1;
        }
        for (int i = 3; i * i <= n; i = i + 2) {
            if (arr[i] == 0) {
                for (int j = i * i; j <= n; j = j + i) {
                    arr[j] = 1;
                }

            }
        }
    }

    static int dfss(int i)
    {
        if(dp[i]!=-1)
            return dp[i];

        int maxd=0;
        for(Integer nbr:hm.get(i))
        {
           int d = 1+ dfss(nbr);
           maxd=Math.max(maxd,d);
        }
        max=Math.max(maxd,max);
        return dp[i]=maxd;

    }


   static int dp[];
    static int max=0;
    static HashMap<Integer,ArrayList<Integer>>hm;
    public static void main(String[] args) throws Exception {
        FastReader sc = new FastReader();

        Clock clock = new Clock();
        clock.start();
        int n=sc.nextInt();
        int m=sc.nextInt();
        String arr[]=new String[n];
        int crr[]=new int[n];
        long ans=1;
        for (int i = 0; i <n ; i++) {
            arr[i]=sc.nextLine();
        }
        for (int i = 0; i <m ; i++) {

            HashSet<Character>set=new HashSet<>();
            for (int j = 0; j <n ; j++) {
                set.add(arr[j].charAt(i));
            }
            if(set.size()>0)
            ans = (ans*(set.size()))%mod;
        }
        System.out.println(ans);





    }}



class Pair {

    int a;
    int b;

    Pair(int a, int b) {
        this.a = a;
        this.b = b;
    }
}
class DSU
{
    int parent[];
    int rank[];
    DSU(int n)
    {
        this.parent=new int[n];
        this.rank=new int[n];
        Arrays.fill(parent,-1);
        Arrays.fill(rank,1);
    }

    int find(int s1)
    {
        if(parent[s1]==-1)
            return s1;
        return parent[s1]=find(parent[s1]);
    }

    void unite(int s1,int s2)
    {
        int p1=this.find(s1);
        int p2=this.find(s2);
        if(p1==p2)
            return;
        if(rank[p1]>rank[p2])
        {
            parent[p2]=p1;
            rank[p1]+=rank[p2];
        }
        else
        {
            parent[p1]=p2;
            rank[p2]+=rank[p1];
        }
    }


}


class Graph {

    HashMap<Integer, ArrayList<Integer>> hm;

    Graph() {
        hm = new HashMap<>();
    }

    Graph(int n) {

        hm = new HashMap<>();
        for (int i = 0; i < n; i++) {
            hm.put(i, new ArrayList<Integer>());
        }
    }

    // function for adding an edge.................................................
    public void addEdge(int a, int b, boolean isDir) {
        if (isDir) {
            if (hm.containsKey(a)) {
                hm.get(a).add(b);
            } else {
                hm.put(a, new ArrayList<>(Arrays.asList(b)));
            }
        } else {
            if (hm.containsKey(a)) {
                hm.get(a).add(b);
            } else if (!hm.containsKey(a)) {
                hm.put(a, new ArrayList<>(Arrays.asList(b)));
            }

            if (hm.containsKey(b)) {
                hm.get(b).add(a);
            } else if (!hm.containsKey(b)) {
                hm.put(b, new ArrayList<>(Arrays.asList(a)));
            }
        }
    }


}

// out.println(al.toString().replaceAll("[\\[|\\]|,]",""));