import java.util.HashSet;

import java.util.Scanner;

public class Main{

    public static void main(String[] args)    {

        Scanner reader=new Scanner(System.in);

        HashSet set=new HashSet();

        int N=reader.nextInt();

        int M=reader.nextInt();

        reader.nextLine();

        String str[]=new String[N];

        for(int i=0;i<N;i++){

            str[i]=reader.nextLine();

            set.add(str[i]);

        }

        System.out.println(set.size());

    }

}