import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class AppendAndDelete {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.next();
        String t = in.next();
        int k = in.nextInt();
     		int commonLength = 0;

		for (int i = 0; i < java.lang.Math.min(s.length(), t.length()); i++) {
			if (s.charAt(i) == t.charAt(i))
				commonLength++;
			else
				break;
		}
		if ((s.length() + t.length() - 2 * commonLength) > k) {
			System.out.println("No");
		} else if (((s.length() + t.length() - 2 * commonLength) % 2 == k % 2) || (s.length() + t.length() - k) < 0) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}
    }
}

Create AppendAndDelete.java