import java.util.*;

public class Main {
	public static boolean areKAnagrams(String str1, String str2, int k) {
	   //check if characters are equal
	if(str1.length()!=str2.length())
	return false;
	
	//make frequency map of any 1 string
	HashMap<Character,Integer> map = new HashMap<>();
	
	for(int i= 0 ;i < str1.length();i++){
	    char ch = str1.charAt(i);
	    map.put(ch , map.getOrDefault(ch,0)+1);
	}
	
	//now traverse the 2nd string and start removing from HM
	for(int i =0 ; i< str2.length();i++){
	    char ch = str2.charAt(i);
	    
	    if(map.getOrDefault(ch,0) >0)
	    map.put(ch , map.get(ch)-1);
	    
	}
	//add all positive frequency 
        int count  = 0 ;
        for(char ch : map.keySet())
        count+= map.get(ch);
        
        return count >k ? false : true;
	}

	public static void main(String[] args) {

		Scanner s = new Scanner(System.in);
		String str1 = s.next();
		String str2 = s.next();
		int k = s.nextInt();
		System.out.println(areKAnagrams(str1, str2, k));

	}

}