import java.util.*;

public class Main {

	public static int solution(String s, int k){
		
		return atmostK_subtrings(s , k) - atmostK_subtrings(s , k-1);
	}
	
	public static int atmostK_subtrings(String s , int k){
	    HashMap<Character,Integer> map1 = new HashMap<>();
        
        int ans = 0 ;
 
        //pointers to keep track of window
        int i = 0 , j = 0;
 
 
        //acquiring and releasing while traversing the array
        for(i = 0 ; i< s.length(); i++){
            //storing in map and updating ccc
            char ch = s.charAt(i);
            map1.put(ch,map1.getOrDefault(ch,0)+1);
 
            //if at any moment the substring becomes invalid we go in this loop to remove the extra character from the back
            while(map1.size()>k){
                
                //removing character & updating ccc
                char temp = s.charAt(j);
                
                //updating ccc
 
                if(map1.get(temp) == 1)
                map1.remove(temp);
                else
                map1.put(temp , map1.get(temp)-1);
 
                j++;
            }
            
            //adding all substrings of the current unique substring
            ans += i - j+1;
        }
 
        return ans;
	}
	
	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);
        String str = scn.next();
        int k = scn.nextInt();
		System.out.println(solution(str,k));
	}

}