import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
        String T = in.nextLine();
      int A = 0;

for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
}

System.out.println(S.length()-A);
        }
    } import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
        String T = in.nextLine();
      int A = 0;

for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
}

System.out.println(S.length()-A);
        }
    } Main public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
        String T = in.nextLine();
      int A = 0;

for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
}

System.out.println(S.length()-A);
        } main {
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
        String T = in.nextLine();
      int A = 0;

for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
}

System.out.println(S.length()-A);
        } Scanner in = new Scanner(System.in); in new Scanner(System.in) String S = in.nextLine(); S in.nextLine() in.nextLine in String T = in.nextLine(); T in.nextLine() in.nextLine in int A = 0; A 0 for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
} int count = 0; int count = 0; count 0 count < S.length() count S.length() S.length S count++ count++ count {
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
} {
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
} if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 } S.charAt(count) == T.charAt(count) S.charAt(count) S.charAt S count T.charAt(count) T.charAt T count {
  A = A +1 ;
 } A = A +1 A A +1 A 1 System.out.println(S.length()-A) System.out.println System.out System System.out S.length()-A S.length() S.length S A String[] args args public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
        String T = in.nextLine();
      int A = 0;

for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
}

System.out.println(S.length()-A);
        }
    } public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
        String T = in.nextLine();
      int A = 0;

for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
}

System.out.println(S.length()-A);
        }
    } Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String S = in.nextLine();
        String T = in.nextLine();
      int A = 0;

for (int count = 0; count < S.length(); count++){
 if(S.charAt(count) == T.charAt(count)){
  A = A +1 ;
 }
}

System.out.println(S.length()-A);
        }
    }