import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!

        Scanner sc = new Scanner (System.in);
        
    String x=sc.nextLine();
    String y=sc.nextLine();
    
    int c=0;
    int z=0;
    
  for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  }
  System.out.println(c);
    
        
    
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!

        Scanner sc = new Scanner (System.in);
        
    String x=sc.nextLine();
    String y=sc.nextLine();
    
    int c=0;
    int z=0;
    
  for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  }
  System.out.println(c);
    
        
    
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!

        Scanner sc = new Scanner (System.in);
        
    String x=sc.nextLine();
    String y=sc.nextLine();
    
    int c=0;
    int z=0;
    
  for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  }
  System.out.println(c);
    
        
    
    } main {
        // Your code here!

        Scanner sc = new Scanner (System.in);
        
    String x=sc.nextLine();
    String y=sc.nextLine();
    
    int c=0;
    int z=0;
    
  for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  }
  System.out.println(c);
    
        
    
    } Scanner sc = new Scanner (System.in); sc new Scanner (System.in) String x=sc.nextLine(); x sc.nextLine() sc.nextLine sc String y=sc.nextLine(); y sc.nextLine() sc.nextLine sc int c=0; c 0 int z=0; z 0 for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  } int i=0; int i=0; i 0 i<x.length() i x.length() x.length x i++ i++ i {
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  } {
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  } char xx=x.charAt(i); xx x.charAt(i) x.charAt x i char yy=y.charAt(i); yy y.charAt(i) y.charAt y i if(xx!=yy){
        c++;
      } xx!=yy xx yy {
        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) throws Exception {
        // Your code here!

        Scanner sc = new Scanner (System.in);
        
    String x=sc.nextLine();
    String y=sc.nextLine();
    
    int c=0;
    int z=0;
    
  for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  }
  System.out.println(c);
    
        
    
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!

        Scanner sc = new Scanner (System.in);
        
    String x=sc.nextLine();
    String y=sc.nextLine();
    
    int c=0;
    int z=0;
    
  for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  }
  System.out.println(c);
    
        
    
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!

        Scanner sc = new Scanner (System.in);
        
    String x=sc.nextLine();
    String y=sc.nextLine();
    
    int c=0;
    int z=0;
    
  for(int i=0;i<x.length();i++){
      char xx=x.charAt(i);
      char yy=y.charAt(i);
      
      if(xx!=yy){
        c++;
      }
      
      
  }
  System.out.println(c);
    
        
    
    }
}
