import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String s = input.next();
        String t = input.next();
        int counter = 0;
        int j = 0;
        for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        }
        System.out.println(counter);
    }
} import java.util.Scanner; Scanner java.util public class Main{
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String s = input.next();
        String t = input.next();
        int counter = 0;
        int j = 0;
        for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        }
        System.out.println(counter);
    }
} Main public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String s = input.next();
        String t = input.next();
        int counter = 0;
        int j = 0;
        for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        }
        System.out.println(counter);
    } main {
        Scanner input = new Scanner(System.in);
        String s = input.next();
        String t = input.next();
        int counter = 0;
        int j = 0;
        for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        }
        System.out.println(counter);
    } Scanner input = new Scanner(System.in); input new Scanner(System.in) String s = input.next(); s input.next() input.next input String t = input.next(); t input.next() input.next input int counter = 0; counter 0 int j = 0; j 0 for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        } int i = 0; int i = 0; i 0 i < s.length() i s.length() s.length s i++ i++ i {
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        } {
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        } if(s.charAt(i) != t.charAt(j))
                    counter++; s.charAt(i) != t.charAt(j) s.charAt(i) s.charAt s i t.charAt(j) t.charAt t j counter++ counter j++ j System.out.println(counter) System.out.println System.out System System.out counter String[] args args public class Main{
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String s = input.next();
        String t = input.next();
        int counter = 0;
        int j = 0;
        for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        }
        System.out.println(counter);
    }
} public class Main{
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String s = input.next();
        String t = input.next();
        int counter = 0;
        int j = 0;
        for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        }
        System.out.println(counter);
    }
} Main
import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String s = input.next();
        String t = input.next();
        int counter = 0;
        int j = 0;
        for(int i = 0; i < s.length();i++){
                if(s.charAt(i) != t.charAt(j))
                    counter++;
            j++;
        }
        System.out.println(counter);
    }
}
