After getting kicked out of her reporting job for not knowing the alphabet, Bessie has decided to attend school at the Fillet and Eggs Eater Academy. She has been making good progress with her studies and now knows the first k English letters.

Each morning, Bessie travels to school along a sidewalk consisting of m + n tiles. In order to help Bessie review, Mr. Moozing has labeled each of the first m sidewalk tiles with one of the first k lowercase English letters, spelling out a string t. Mr. Moozing, impressed by Bessie's extensive knowledge of farm animals, plans to let her finish labeling the last n tiles of the sidewalk by herself.

Consider the resulting string s (|s| = m + n) consisting of letters labeled on tiles in order from home to school. For any sequence of indices p1 < p2 < ... < pq we can define subsequence of the string s as string sp1sp2... spq. Two subsequences are considered to be distinct if they differ as strings. Bessie wants to label the remaining part of the sidewalk such that the number of distinct subsequences of tiles is maximum possible. However, since Bessie hasn't even finished learning the alphabet, she needs your help!

Note that empty subsequence also counts.

Input

The first line of the input contains two integers n and k (0 ≤ n ≤ 1 000 000, 1 ≤ k ≤ 26).

The second line contains a string t (|t| = m, 1 ≤ m ≤ 1 000 000) consisting of only first k lowercase English letters.

Output

Determine the maximum number of distinct subsequences Bessie can form after labeling the last n sidewalk tiles each with one of the first k lowercase English letters. Since this number can be rather large, you should print it modulo 109 + 7.

Please note, that you are not asked to maximize the remainder modulo 109 + 7! The goal is to maximize the initial value and then print the remainder.

Examples

Input

1 3
ac


Output

8


Input

0 2
aaba


Output

10

Note

In the first sample, the optimal labeling gives 8 different subsequences: "" (the empty string), "a", "c", "b", "ac", "ab", "cb", and "acb".

<image>

In the second sample, the entire sidewalk is already labeled. The are 10 possible different subsequences: "" (the empty string), "a", "b", "aa", "ab", "ba", "aaa", "aab", "aba", and "aaba". Note that some strings, including "aa", can be obtained with multiple sequences of tiles, but are only counted once.
import java.util.*;
import java.io.*;
import java.awt.Point;
import java.math.BigDecimal;
import java.math.BigInteger;

import static java.lang.Math.*;


public class E implements Runnable{
	
	final static Random rnd = new Random();
	
	// SOLUTION!!! 
	// HACK ME PLEASE IF YOU CAN!!!
	// PLEASE!!!
	// PLEASE!!!
	// PLEASE!!!
	
	static final int MODULO = 1000 * 1000 * 1000 + 7;
	static final BigInteger MODULO_BIG = BigInteger.valueOf(MODULO);
	
	void solve() {
		int n = readInt();
		int k = readInt();
		
		char[] t = readCharArray();
		
		int[] s = new int[t.length + n];
		Arrays.fill(s, -1);
		for (int i = 0; i < t.length; ++i) {
			s[i] = t[i] - 'a';
		}
		
		int[] answers = new int[s.length];
		int[] prefixAnswers = new int[s.length + 1];
		prefixAnswers[0] = 1;
		
		int[] lasts = new int[k];
		Arrays.fill(lasts, -1);
		
		for (int i = 0; i < s.length; ++i) {
			if (s[i] == -1) {
				for (int cur = 0; cur < lasts.length; ++cur) {
					if (s[i] == -1 || lasts[s[i]] > lasts[cur]) {
						s[i] = cur;
					}
				}
			}
			
			int cur = s[i];
			
			long increment = 0;
			
			increment += prefixAnswers[i];
			if (lasts[cur] >= 0) increment -= prefixAnswers[lasts[cur]];
			
			increment %= MODULO;
			
			lasts[cur] = i;
			
			answers[i] = (int) (increment + MODULO) % MODULO;
			prefixAnswers[i + 1] = (prefixAnswers[i] + answers[i]) % MODULO;
		}
		
		int answer = prefixAnswers[s.length];
		out.println(answer);
	}
	
	/////////////////////////////////////////////////////////////////////
	
	final boolean FIRST_INPUT_STRING = false;
	final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;
	
	final static int MAX_STACK_SIZE = 128;
	
	/////////////////////////////////////////////////////////////////////
	
	public void run(){
		try{
			timeBegin = System.currentTimeMillis();
			Locale.setDefault(Locale.US);
			
			init();
			
			if (ONLINE_JUDGE) {
				solve();
			} else {
				while (true) {
					try {
						solve();
						out.println();
					} catch (NumberFormatException e) {
						break;
					} catch (NullPointerException e) {
						if (FIRST_INPUT_STRING) break;
						else throw e;
					}
				}
			}
			
			out.close();
			time();
		}catch (Exception e){
			e.printStackTrace(System.err);
			System.exit(-1);
		}
	}
	
	/////////////////////////////////////////////////////////////////////
	
	BufferedReader in;
	OutputWriter out;
	StringTokenizer tok = new StringTokenizer("");
	
	public static void main(String[] args){
		new Thread(null, new E(), "", MAX_STACK_SIZE * (1L << 20)).start();
	}
	
	/////////////////////////////////////////////////////////////////////
	
	void init() throws FileNotFoundException{
		Locale.setDefault(Locale.US);
		
		if (ONLINE_JUDGE){
			in = new BufferedReader(new InputStreamReader(System.in));
			out = new OutputWriter(System.out);
		}else{
			in = new BufferedReader(new FileReader("input.txt"));
			out = new OutputWriter("output.txt");
		}
	}
	
	////////////////////////////////////////////////////////////////
	
	long timeBegin, timeEnd;

	void time(){
		timeEnd = System.currentTimeMillis();
		System.err.println("Time = " + (timeEnd - timeBegin));
	}
	
	void debug(Object... objects){
		if (ONLINE_JUDGE){
			for (Object o: objects){
				System.err.println(o.toString());
			}
		}
	}
	
	/////////////////////////////////////////////////////////////////////
	
	String delim = " ";
	
	String readLine() {
		try {
			return in.readLine();
		} catch (IOException e) {
			throw new RuntimeIOException(e);
		}
	}
	
	String readString() {
		try {
			while(!tok.hasMoreTokens()){
				tok = new StringTokenizer(readLine());
			}
			
			return tok.nextToken(delim);
		} catch (NullPointerException e) {
			return null;
		}
	}
	
	/////////////////////////////////////////////////////////////////
	
	final char NOT_A_SYMBOL = '\0';
	
	char readChar() {
		try {
			int intValue = in.read();
			
			if (intValue == -1){
				return NOT_A_SYMBOL;
			}
			
			return (char) intValue;
		} catch (IOException e) {
			throw new RuntimeIOException(e);
		}
	}
	
	char[] readCharArray() {
		return readLine().toCharArray();
	}
	
	char[][] readCharField(int rowsCount) {
		char[][] field = new char[rowsCount][];
		for (int row = 0; row < rowsCount; ++row) {
			field[row] = readCharArray();
		}
		
		return field;
	}
	
	/////////////////////////////////////////////////////////////////
	
	int readInt() {
		return Integer.parseInt(readString());
	}
	
	int[] readIntArray(int size) {
		int[] array = new int[size];
		
		for (int index = 0; index < size; ++index){
			array[index] = readInt();
		}
		
		return array;
	}
	
	int[] readSortedIntArray(int size) {
		Integer[] array = new Integer[size];
		
		for (int index = 0; index < size; ++index) {
			array[index] = readInt();
		}
		Arrays.sort(array);
		
		int[] sortedArray = new int[size];
		for (int index = 0; index < size; ++index) {
			sortedArray[index] = array[index];
		}
		
		return sortedArray;
	}
	
	int[] readIntArrayWithDecrease(int size) {
		int[] array = readIntArray(size);
		
		for (int i = 0; i < size; ++i) {
			array[i]--;
		}
		
		return array;
	}
	
	///////////////////////////////////////////////////////////////////
	
	int[][] readIntMatrix(int rowsCount, int columnsCount) {
		int[][] matrix = new int[rowsCount][];
		
		for (int rowIndex = 0; rowIndex < rowsCount; ++rowIndex) {
			matrix[rowIndex] = readIntArray(columnsCount);
		}
		
		return matrix;
	}
	
	int[][] readIntMatrixWithDecrease(int rowsCount, int columnsCount) {
		int[][] matrix = new int[rowsCount][];
		
		for (int rowIndex = 0; rowIndex < rowsCount; ++rowIndex) {
			matrix[rowIndex] = readIntArrayWithDecrease(columnsCount);
		}
		
		return matrix;
	}
	
	///////////////////////////////////////////////////////////////////
	
	long readLong() {
		return Long.parseLong(readString());
	}
	
	long[] readLongArray(int size) {
		long[] array = new long[size];
		
		for (int index = 0; index < size; ++index){
			array[index] = readLong();
		}
		
		return array;
	}
	
	////////////////////////////////////////////////////////////////////
	
	double readDouble() {
		return Double.parseDouble(readString());
	}
	
	double[] readDoubleArray(int size) {
		double[] array = new double[size];
		
		for (int index = 0; index < size; ++index){
			array[index] = readDouble();
		}
		
		return array;
	}
	
	////////////////////////////////////////////////////////////////////
		
	BigInteger readBigInteger() {
		return new BigInteger(readString());
	}
	
	BigDecimal readBigDecimal() {
		return new BigDecimal(readString());
	}
	
	/////////////////////////////////////////////////////////////////////
	
	Point readPoint() {
		int x = readInt();
		int y = readInt();
		return new Point(x, y);
	}
	
	Point[] readPointArray(int size) {
		Point[] array = new Point[size];
		
		for (int index = 0; index < size; ++index){
			array[index] = readPoint();
		}
		
		return array;
	}
	
	/////////////////////////////////////////////////////////////////////
	
	List<Integer>[] readGraph(int vertexNumber, int edgeNumber) {
		@SuppressWarnings("unchecked")
		List<Integer>[] graph = new List[vertexNumber];
		
		for (int index = 0; index < vertexNumber; ++index){
			graph[index] = new ArrayList<Integer>();
		}
		
		while (edgeNumber-- > 0){
			int from = readInt() - 1;
			int to = readInt() - 1;
			
			graph[from].add(to);
			graph[to].add(from);
		}
		
		return graph;
	}
	
	/////////////////////////////////////////////////////////////////////
	
	static class IntIndexPair {
		
		static Comparator<IntIndexPair> increaseComparator = new Comparator<IntIndexPair>() {
			
			@Override
			public int compare(IntIndexPair indexPair1, IntIndexPair indexPair2) {
				int value1 = indexPair1.value;
				int value2 = indexPair2.value;
				
				if (value1 != value2) return value1 - value2;
				
				int index1 = indexPair1.index;
				int index2 = indexPair2.index;
				
				return index1 - index2;
			}
		};
		
		static Comparator<IntIndexPair> decreaseComparator = new Comparator<IntIndexPair>() {
			
			@Override
			public int compare(IntIndexPair indexPair1, IntIndexPair indexPair2) {
				int value1 = indexPair1.value;
				int value2 = indexPair2.value;
				
				if (value1 != value2) return -(value1 - value2);
				
				int index1 = indexPair1.index;
				int index2 = indexPair2.index;
				
				return index1 - index2;
			}
		};
		
		int value, index;

		public IntIndexPair(int value, int index) {
			super();
			this.value = value;
			this.index = index;
		}		
		
		public int getRealIndex() {
			return index + 1;
		}
	}
	
	IntIndexPair[] readIntIndexArray(int size) {
		IntIndexPair[] array = new IntIndexPair[size];
		
		for (int index = 0; index < size; ++index) {
			array[index] = new IntIndexPair(readInt(), index);
		}
		
		return array;
	}
	
	/////////////////////////////////////////////////////////////////////
	
	static class OutputWriter extends PrintWriter {

		final int DEFAULT_PRECISION = 12;
		
		protected int precision;
		protected String format, formatWithSpace;
		
		{
			precision = DEFAULT_PRECISION;
			
			format = createFormat(precision);
			formatWithSpace = format + " ";
		}
		
		public OutputWriter(OutputStream out) {
			super(out);
		}

		public OutputWriter(String fileName) throws FileNotFoundException {
			super(fileName);
		}
		
		public int getPrecision() {
			return precision;
		}

		public void setPrecision(int precision) {
			precision = max(0, precision);
			this.precision = precision;
			
			format = createFormat(precision);
			formatWithSpace = format + " ";
		}
		
		private String createFormat(int precision){
			return "%." + precision + "f";
		}
		
		@Override
		public void print(double d){
			printf(format, d);
		}
		
		public void printWithSpace(double d){
			printf(formatWithSpace, d);
		}

		public void printAll(double...d){
			for (int i = 0; i < d.length - 1; ++i){
				printWithSpace(d[i]);
			}
			
			print(d[d.length - 1]);
		}
		
		@Override
		public void println(double d){
			printlnAll(d);
		}
		
		public void printlnAll(double... d){
			printAll(d);
			println();
		}
	}
	
	/////////////////////////////////////////////////////////////////////
	
	static class RuntimeIOException extends RuntimeException {

		/**
		 * 
		 */
		private static final long serialVersionUID = -6463830523020118289L;

		public RuntimeIOException(Throwable cause) {
			super(cause);
		}
	}
	
	/////////////////////////////////////////////////////////////////////
	//////////////// Some useful constants and functions ////////////////
	/////////////////////////////////////////////////////////////////////
	
	static final int[][] steps = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}}; 
	static final int[][] steps8 = {
			{-1, 0}, {1, 0}, {0, -1}, {0, 1},
			{-1, -1}, {1, 1}, {1, -1}, {-1, 1}
	};
	
	static final boolean checkCell(int row, int rowsCount, int column, int columnsCount) {
		return checkIndex(row, rowsCount) && checkIndex(column, columnsCount);
	}
	
	static final boolean checkIndex(int index, int lim){
		return (0 <= index && index < lim);
	}
	
	/////////////////////////////////////////////////////////////////////
	
	static final boolean checkBit(int mask, int bit){
		return (mask & (1 << bit)) != 0;
	}
	
	/////////////////////////////////////////////////////////////////////
	
	static final long getSum(int[] array) {
		long sum = 0;
		for (int value: array) {
			sum += value;
		}
		
		return sum;
	}
	
	static final Point getMinMax(int[] array) {
		int min = array[0];
		int max = array[0];
		
		for (int index = 0, size = array.length; index < size; ++index, ++index) {
			int value = array[index];
			
			if (index == size - 1) {
				min = min(min, value);
				max = max(max, value);
			} else {
				int otherValue = array[index + 1];
				
				if (value <= otherValue) {
					min = min(min, value);
					max = max(max, otherValue);
				} else {
					min = min(min, otherValue);
					max = max(max, value);
				}
			}
		}
		
		return new Point(min, max);
	}
	
	/////////////////////////////////////////////////////////////////////
	
	static class IdMap<KeyType> extends HashMap<KeyType, Integer> {

		/**
		 * 
		 */
		private static final long serialVersionUID = -3793737771950984481L;

		public IdMap() {
			super();
		}
		
		int getId(KeyType key) {
			Integer id = super.get(key);
			if (id == null) {
				super.put(key, id = size());
			}
			
			return id;
		}
	}
}

