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 count = 0;
        for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        }
        System.out.println(count);
    }
} 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 count = 0;
        for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        }
        System.out.println(count);
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int count = 0;
        for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        }
        System.out.println(count);
    } main {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int count = 0;
        for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        }
        System.out.println(count);
    } 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 count = 0; count 0 for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        } int i = 0; int i = 0; i 0 i <= s.length() - 1 i s.length() - 1 s.length() s.length s 1 i++ i++ i {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        } {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        } char c = s.charAt(i); c s.charAt(i) s.charAt s i char d = t.charAt(i); d t.charAt(i) t.charAt t i if(c != d) {
                count++;
            } c != d c d {
                count++;
            } count++ count System.out.println(count) System.out.println System.out System System.out count 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 count = 0;
        for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        }
        System.out.println(count);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String t = scanner.nextLine();
        int count = 0;
        for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        }
        System.out.println(count);
    }
} 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 count = 0;
        for (int i = 0; i <= s.length() - 1; i++) {
            char c = s.charAt(i);
            char d = t.charAt(i);
            if(c != d) {
                count++;
            }
        }
        System.out.println(count);
    }
}