Problem:
Score : 100 points

Problem Statement

Kyoto University Programming Contest is a programming contest voluntarily held by some Kyoto University students.
This contest is abbreviated as Kyoto University Programming Contest and called KUPC.

source: Kyoto University Programming Contest Information

The problem-preparing committee met to hold this year's KUPC and N problems were proposed there.
The problems are numbered from 1 to N and the name of i-th problem is P_i.
However, since they proposed too many problems, they decided to divide them into some sets for several contests.

They decided to divide this year's KUPC into several KUPCs by dividing problems under the following conditions.

One KUPC provides K problems.

Each problem appears at most once among all the KUPCs.

All the first letters of the problem names in one KUPC must be different.

You, one of the committee members, want to hold as many KUPCs as possible.
Write a program to find the maximum number of KUPCs that can be held this year.

Constraints

1 \leq N \leq 10^4

1 \leq K \leq 26

1 \leq |P_i| \leq 10

All characters in P_i are capital letters.

Note that, for each i and j (1 \leq i < j \leq N),
P_i \neq P_j are not necessarily satisfied.

Input

The input is given from Standard Input in the following format:

N K
P_1
:
P_N

Output

Print the maximum number of KUPCs that can be held on one line.

Sample Input 1

9 3
APPLE
ANT
ATCODER
BLOCK
BULL
BOSS
CAT
DOG
EGG

For example, three KUPCs can be held by dividing the problems as follows.

First: APPLE, BLOCK, CAT

Second: ANT, BULL, DOG

Third: ATCODER, BOSS, EGG

Sample Output 1

3

Sample Input 2

3 2
KU
KYOUDAI
KYOTOUNIV

Sample Output 2

0

No KUPC can be held.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.Closeable;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map.Entry;
import java.util.Random;
import java.util.TreeMap;

public class Main {
	static ContestScanner in;static Writer out;static StringBuilder sb=new StringBuilder();
	public static void main(String[] args)
	{try{in=new ContestScanner();out=new Writer();Main solve=new Main();solve.solve();
	in.close();out.flush();out.close();}catch(IOException e){e.printStackTrace();}}
	static void dump(int[]a){sb.setLength(0);for(int i=0;i<a.length;i++)
	sb.append(a[i]).append("\t");out.println(sb.toString().trim());}
	static void dump(int[]a,int n){for(int i=0;i<a.length;i++)out.printf("%"+n+"d ",a[i]);out.println();}
	static void dump(long[]a){for(int i=0;i<a.length;i++)out.print(a[i]+" ");out.println();}
	static long pow(long a,int n){long r=1;while(n>0){if((n&1)==1)r*=a;a*=a;n>>=1;}return r;}
	static String itob(int a,int l){return String.format("%"+l+"s",Integer.toBinaryString(a)).replace(' ','0');}
	static void sort(int[]a){m_sort(a,0,a.length,new int[a.length]);}
	static void sort(int[]a,int l){m_sort(a,0,l,new int[l]);}
	static void sort(int[]a,int l,int[]buf){m_sort(a,0,l,buf);}
	static void sort(int[]a,int s,int l,int[]buf){m_sort(a,s,l,buf);}
	static void m_sort(int[]a,int s,int sz,int[]b)
	{if(sz<7){for(int i=s;i<s+sz;i++)for(int j=i;j>s&&a[j-1]>a[j];j--)swap(a, j, j-1);return;}
	m_sort(a,s,sz/2,b);m_sort(a,s+sz/2,sz-sz/2,b);int x=s;int l=s,r=s+sz/2;final int le=s+sz/2,re=s+sz;
	while(l<le&&r<re){if(a[l]>a[r])b[x++]=a[r++];else b[x++]=a[l++];}
	while(r<re)b[x++]=a[r++];while(l<le)b[x++]=a[l++];for(int i=s;i<s+sz;i++)a[i]=b[i];
	} /* qsort(3.5s)<<msort(9.5s)<<<shuffle+qsort(17s)<Arrays.sort(Integer)(20s) */
	static void sort(long[]a){m_sort(a,0,a.length,new long[a.length]);}
	static void sort(long[]a,int l){m_sort(a,0,l,new long[l]);}
	static void sort(long[]a,int l,long[]buf){m_sort(a,0,l,buf);}
	static void sort(long[]a,int s,int l,long[]buf){m_sort(a,s,l,buf);}
	static void m_sort(long[]a,int s,int sz,long[]b)
	{if(sz<7){for(int i=s;i<s+sz;i++)for(int j=i;j>s&&a[j-1]>a[j];j--)swap(a, j, j-1);return;}
	m_sort(a,s,sz/2,b);m_sort(a,s+sz/2,sz-sz/2,b);int x=s;int l=s,r=s+sz/2;final int le=s+sz/2,re=s+sz;
	while(l<le&&r<re){if(a[l]>a[r])b[x++]=a[r++];else b[x++]=a[l++];}
	while(r<re)b[x++]=a[r++];while(l<le)b[x++]=a[l++];for(int i=s;i<s+sz;i++)a[i]=b[i];}
	static void swap(long[]a,int i,int j){final long t=a[i];a[i]=a[j];a[j]=t;}
	static void swap(int[]a,int i,int j){final int t=a[i];a[i]=a[j];a[j]=t;}
	static int binarySearchSmallerMax(int[]a,int v)// get maximum index which a[idx]<=v
	{int l=-1,r=a.length-1,s=0;while(l<=r){int m=(l+r)/2;if(a[m]>v)r=m-1;else{l=m+1;s=m;}}return s;}
	static int binarySearchSmallerMax(int[]a,int v,int l,int r)
	{int s=-1;while(l<=r){int m=(l+r)/2;if(a[m]>v)r=m-1;else{l=m+1;s=m;}}return s;}
	List<Integer>[]randomTree(int n,Random r){List<Integer>[]g=graph(n);
	for(int i=1;i<n;i++){int p=r.nextInt(i);g[p].add(i);g[i].add(p);}return g;}
	static List<Integer>[]graph(int n){List<Integer>[]g=new List[n];
	for(int i=0;i<n;i++)g[i]=new ArrayList<>();return g;}
	void solve() throws NumberFormatException, IOException{
		int n = in.nextInt();
		int k = in.nextInt();
		int[] alp = new int[26];
		for(int i=0; i<n; i++){
			char c = in.nextToken().charAt(0);
			alp[c-'A']++;
		}
		Arrays.sort(alp);
		int cnt = 0;
		while(true){
			int tk = 0;
			for(int i=25; i>=0; i--){
				if(alp[i]>0){
					alp[i]--;
					tk++;
					if(tk==k) break;
				}
			}
			if(tk<k) break;
			cnt++;
		}
		System.out.println(cnt);
		
	}
	
}

class MultiSet<T> extends HashMap<T, Integer>{
	@Override public Integer get(Object key){return containsKey(key)?super.get(key):0;}
	public void add(T key,int v){put(key,get(key)+v);}
	public void add(T key){put(key,get(key)+1);}
	public void sub(T key){final int v=get(key);if(v==1)remove(key);else put(key,v-1);}
	public MultiSet<T> merge(MultiSet<T> set)
	{MultiSet<T>s,l;if(this.size()<set.size()){s=this;l=set;}else{s=set;l=this;}
	for(Entry<T,Integer>e:s.entrySet())l.add(e.getKey(),e.getValue());return l;}
}
class OrderedMultiSet<T> extends TreeMap<T, Integer>{
	@Override public Integer get(Object key){return containsKey(key)?super.get(key):0;}
	public void add(T key,int v){put(key,get(key)+v);}
	public void add(T key){put(key,get(key)+1);}
	public void sub(T key){final int v=get(key);if(v==1)remove(key);else put(key,v-1);}
	public OrderedMultiSet<T> merge(OrderedMultiSet<T> set)
	{OrderedMultiSet<T>s,l;if(this.size()<set.size()){s=this;l=set;}else{s=set;l=this;}
	while(!s.isEmpty()){l.add(s.firstEntry().getKey(),s.pollFirstEntry().getValue());}return l;}
}
class Pair implements Comparable<Pair>{
	int a,b;final int hash;Pair(int a,int b){this.a=a;this.b=b;hash=(a<<16|a>>16)^b;}
	public boolean equals(Object obj){Pair o=(Pair)(obj);return a==o.a&&b==o.b;}
	public int hashCode(){return hash;}
	public int compareTo(Pair o){if(a!=o.a)return a<o.a?-1:1;else if(b!=o.b)return b<o.b?-1:1;return 0;}
}
class Timer{
	long time;public void set(){time=System.currentTimeMillis();}
	public long stop(){return time=System.currentTimeMillis()-time;}
	public void print(){System.out.println("Time: "+(System.currentTimeMillis()-time)+"ms");}
	@Override public String toString(){return"Time: "+time+"ms";}
}
class Writer extends PrintWriter{
	public Writer(String filename)throws IOException
	{super(new BufferedWriter(new FileWriter(filename)));}
	public Writer()throws IOException{super(System.out);}
}
class ContestScanner implements Closeable{
	private BufferedReader in;private int c=-2;
	public ContestScanner()throws IOException 
	{in=new BufferedReader(new InputStreamReader(System.in));}
	public ContestScanner(String filename)throws IOException
	{in=new BufferedReader(new InputStreamReader(new FileInputStream(filename)));}
	public String nextToken()throws IOException {
		StringBuilder sb=new StringBuilder();
		while((c=in.read())!=-1&&Character.isWhitespace(c));
		while(c!=-1&&!Character.isWhitespace(c)){sb.append((char)c);c=in.read();}
		return sb.toString();
	}
	public String readLine()throws IOException{
		StringBuilder sb=new StringBuilder();if(c==-2)c=in.read();
		while(c!=-1&&c!='\n'&&c!='\r'){sb.append((char)c);c=in.read();}
		return sb.toString();
	}
	public long nextLong()throws IOException,NumberFormatException
	{return Long.parseLong(nextToken());}
	public int nextInt()throws NumberFormatException,IOException
	{return(int)nextLong();}
	public double nextDouble()throws NumberFormatException,IOException 
	{return Double.parseDouble(nextToken());}
	public void close() throws IOException {in.close();}
}