import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int l = s.length();
        int ans = 0;
        if (l == 0) {
            System.out.println(ans);
            return;
        }
        for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        }
        System.out.println(ans);
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int l = s.length();
        int ans = 0;
        if (l == 0) {
            System.out.println(ans);
            return;
        }
        for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        }
        System.out.println(ans);
    }
} Main public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int l = s.length();
        int ans = 0;
        if (l == 0) {
            System.out.println(ans);
            return;
        }
        for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        }
        System.out.println(ans);
    } main {

        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int l = s.length();
        int ans = 0;
        if (l == 0) {
            System.out.println(ans);
            return;
        }
        for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        }
        System.out.println(ans);
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) String s = scanner.nextLine(); s scanner.nextLine() scanner.nextLine scanner String t = scanner.nextLine(); t scanner.nextLine() scanner.nextLine scanner int l = s.length(); l s.length() s.length s int ans = 0; ans 0 if (l == 0) {
            System.out.println(ans);
            return;
        } l == 0 l 0 {
            System.out.println(ans);
            return;
        } System.out.println(ans) System.out.println System.out System System.out ans return; for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        } int i = 0; int i = 0; i 0 i< l i l i++ i++ i {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        } {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        } if (s.charAt(i) != t.charAt(i)) {
                ans++;
            } s.charAt(i) != t.charAt(i) s.charAt(i) s.charAt s i t.charAt(i) t.charAt t i {
                ans++;
            } ans++ ans System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int l = s.length();
        int ans = 0;
        if (l == 0) {
            System.out.println(ans);
            return;
        }
        for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        }
        System.out.println(ans);
    }
} public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int l = s.length();
        int ans = 0;
        if (l == 0) {
            System.out.println(ans);
            return;
        }
        for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        }
        System.out.println(ans);
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int l = s.length();
        int ans = 0;
        if (l == 0) {
            System.out.println(ans);
            return;
        }
        for (int i = 0; i< l; i++) {
            if (s.charAt(i) != t.charAt(i)) {
                ans++;
            }
        }
        System.out.println(ans);
    }
}
