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.math.*;
import java.util.*;

/**
 *
 * @author Saju
 *
 */

public class Main {

	private static int dx[] = { 1, 0, -1, 0 };
	private static int dy[] = { 0, -1, 0, 1 };
	private static int dx1[] = { 1, 1, 0, -1, -1, -1, 0, 1 };
	private static int dy1[] = { 0, -1, -1, -1, 0, 1, 1, 1 };

	private static final long INF = Long.MAX_VALUE;
	private static final int INT_INF = Integer.MAX_VALUE;
	private static final long NEG_INF = Long.MIN_VALUE;
	private static final int NEG_INT_INF = Integer.MIN_VALUE;
	private static final double EPSILON = 1e-10;

	private static final long MAX = (long) 1e12;

	private static final long MOD = 1000000007;

	private static final int MAXN = 5000077;
	private static final int MAXA = 6000;
	private static final int MAXLOG = 22;
	private static final double PI = Math.acos(-1);

	public static void main(String[] args) throws IOException {

		InputReader in = new InputReader(System.in);
		// Scanner in = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);

		// InputReader in = new InputReader(new FileInputStream("src/test.in"));
		// PrintWriter out = new PrintWriter(new BufferedWriter(new
		// FileWriter("src/test.out")));

/*



*/

		
		int n = in.nextInt();
		int m = in.nextInt();
		char[][] names = new char[n][m];
		for(int i = 0; i < n; i++) {
			names[i] = in.next().toCharArray();
		}
		
		long cnt = 1;
		
		for(int i = 0; i < m; i++) {
			Set<Character> set = new HashSet<>();
			for(int j = 0; j < n; j++) {
				set.add(names[j][i]);
			}
			long sz = set.size();
			cnt = (cnt * sz) % MOD;
		}
		out.println(cnt);
		
		
		
		in.close();
		out.flush();
		out.close();
		System.exit(0);
	}

	/*
	 * return the number of elements in list that are less than or equal to the val
	 */
	private static long upperBound(List<Long> list, long val) {
		int start = 0;
		int len = list.size();
		int end = len - 1;
		int mid = 0;

		while (true) {
			if (start > end) {
				break;
			}
			mid = (start + end) / 2;
			long v = list.get(mid);
			if (v == val) {
				start = mid;
				while (start < end) {
					mid = (start + end) / 2;
					if (list.get(mid) == val) {
						if (mid + 1 < len && list.get(mid + 1) == val) {
							start = mid + 1;
						} else {
							return mid + 1;
						}
					} else {
						end = mid - 1;
					}
				}
				return start + 1;
			}
			if (v > val) {
				end = mid - 1;
			} else {
				start = mid + 1;
			}
		}
		if (list.get(mid) < val) {
			return mid + 1;
		}
		return mid;
	}

	private static boolean isPalindrome(String str) {
		StringBuilder sb = new StringBuilder();
		sb.append(str);
		String str1 = sb.reverse().toString();
		return str.equals(str1);
	}

	private static String getBinaryStr(long n, int j) {
		String str = Long.toBinaryString(n);
		int k = str.length();
		for (int i = 1; i <= j - k; i++) {
			str = "0" + str;
		}

		return str;
	}

	private static long modInverse(long r) {
		return bigMod(r, MOD - 2, MOD);
	}

	private static long bigMod(long n, long k, long m) {

		long ans = 1;
		while (k > 0) {
			if ((k & 1) == 1) {
				ans = (ans * n) % m;
			}
			n = (n * n) % m;
			k >>= 1;
		}
		return ans;
	}

	private static long ceil(long n, long x) {
		long div = n / x;
		if (div * x != n) {
			div++;
		}
		return div;
	}

	private static int ceil(int n, int x) {
		int div = n / x;
		if (div * x != n) {
			div++;
		}
		return div;
	}

	private static int abs(int x) {
		if (x < 0) {
			return -x;
		}
		return x;
	}

	private static double abs(double x) {
		if (x < 0) {
			return -x;
		}
		return x;
	}

	private static long abs(long x) {
		if (x < 0) {
			return -x;
		}
		return x;
	}

	private static int lcm(int a, int b) {
		return (a * b) / gcd(a, b);
	}

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

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

	private static int log(long x, int base) {
		return (int) (Math.log(x) / Math.log(base));
	}

	private static long min(long a, long b) {
		if (a < b) {
			return a;
		}
		return b;
	}

	private static int min(int a, int b) {
		if (a < b) {
			return a;
		}
		return b;
	}

	private static long max(long a, long b) {
		if (a < b) {
			return b;
		}
		return a;
	}

	private static int max(int a, int b) {
		if (a < b) {
			return b;
		}
		return a;
	}

	private static class InputReader {
		public BufferedReader reader;
		public StringTokenizer tokenizer;

		public InputReader(InputStream stream) {
			reader = new BufferedReader(new InputStreamReader(stream));
			tokenizer = null;
		}

		public String next() {
			try {
				while (tokenizer == null || !tokenizer.hasMoreTokens()) {
					tokenizer = new StringTokenizer(reader.readLine());

				}
			} catch (IOException e) {
				return null;
			}
			return tokenizer.nextToken();
		}

		public String nextLine() {
			String line = null;
			try {
				tokenizer = null;
				line = reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
			return line;
		}

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

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

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

		public boolean hasNext() {
			try {
				while (tokenizer == null || !tokenizer.hasMoreTokens()) {
					tokenizer = new StringTokenizer(reader.readLine());
				}
			} catch (Exception e) {
				return false;
			}
			return true;
		}

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

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

		public int[] nextIntArr1(int n) {
			int arr[] = new int[n + 1];
			for (int i = 1; i <= n; i++) {
				arr[i] = nextInt();
			}
			return arr;
		}

		public long[] nextLongArr1(int n) {
			long arr[] = new long[n + 1];
			for (int i = 1; i <= n; i++) {
				arr[i] = nextLong();
			}
			return arr;
		}

		public void close() {
			try {
				if (reader != null) {
					reader.close();
				}
			} catch (Exception e) {

			}

		}
	}

}
	  	  				 	 	 		 	  	    					