import java.util.Scanner;
public class Main {
    public static int findRotationLevel(String str1, String str2) {
        for (int i = 1; i <= str1.length(); i++) {
            if (str2.contains(str1.substring(i) + str1.substring(0, i))) {
                return i;
            }
        }
        return -1;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String[] str = sc.nextLine().split(" ");
        int rotationLevel = findRotationLevel(str[0], str[1]);

        System.out.println(rotationLevel);
    }
}