
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();

        int c = 0;
        for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        }
        System.out.println(c);
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();

        int c = 0;
        for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        }
        System.out.println(c);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();

        int c = 0;
        for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        }
        System.out.println(c);
    } main {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();

        int c = 0;
        for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        }
        System.out.println(c);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String a = sc.next(); a sc.next() sc.next sc String b = sc.next(); b sc.next() sc.next sc int c = 0; c 0 for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        } int i = 0; int i = 0; i 0 i < b.length() i b.length() b.length b i++ i++ i {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        } {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        } if (b.charAt(i) != a.charAt(i)) {
                c++;
            } b.charAt(i) != a.charAt(i) b.charAt(i) b.charAt b i a.charAt(i) a.charAt a i {
                c++;
            } c++ c System.out.println(c) System.out.println System.out System System.out c String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();

        int c = 0;
        for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        }
        System.out.println(c);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();

        int c = 0;
        for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        }
        System.out.println(c);
    }
} Main

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String a = sc.next();
        String b = sc.next();

        int c = 0;
        for (int i = 0; i < b.length(); i++) {
            if (b.charAt(i) != a.charAt(i)) {
                c++;
            }
        }
        System.out.println(c);
    }
}
