import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String word = sc.nextLine();
        String word1 = sc.nextLine();
        int counter = 0;
        for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        }
        System.out.println(counter);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String word = sc.nextLine();
        String word1 = sc.nextLine();
        int counter = 0;
        for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        }
        System.out.println(counter);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String word = sc.nextLine();
        String word1 = sc.nextLine();
        int counter = 0;
        for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        }
        System.out.println(counter);
    } main {
        Scanner sc = new Scanner(System.in);
        String word = sc.nextLine();
        String word1 = sc.nextLine();
        int counter = 0;
        for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        }
        System.out.println(counter);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String word = sc.nextLine(); word sc.nextLine() sc.nextLine sc String word1 = sc.nextLine(); word1 sc.nextLine() sc.nextLine sc int counter = 0; counter 0 for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        } int p=0; int p=0; p 0 p<word.length() p word.length() word.length word p++ p++ p {
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        } {
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        } if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            } word.charAt(p) != word1.charAt(p) word.charAt(p) word.charAt word p word1.charAt(p) word1.charAt word1 p {
                ++counter;
            } ++counter counter 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 sc = new Scanner(System.in);
        String word = sc.nextLine();
        String word1 = sc.nextLine();
        int counter = 0;
        for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        }
        System.out.println(counter);
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String word = sc.nextLine();
        String word1 = sc.nextLine();
        int counter = 0;
        for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        }
        System.out.println(counter);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String word = sc.nextLine();
        String word1 = sc.nextLine();
        int counter = 0;
        for(int p=0; p<word.length(); p++){
            if(word.charAt(p) != word1.charAt(p)){
                ++counter;
            }

        }
        System.out.println(counter);
    }
}