
import java.util.Scanner;

public class Main {
   public static void main(String[] args) {
       Scanner s= new Scanner(System.in);
       String st = s.nextLine();
       String t = s.nextLine();
       int count = 0, len =st.length();
       for(int i = 0;i < len; ++i) {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       }
       System.out.println(count);
   }
} import java.util.Scanner; Scanner java.util public class Main {
   public static void main(String[] args) {
       Scanner s= new Scanner(System.in);
       String st = s.nextLine();
       String t = s.nextLine();
       int count = 0, len =st.length();
       for(int i = 0;i < len; ++i) {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       }
       System.out.println(count);
   }
} Main public static void main(String[] args) {
       Scanner s= new Scanner(System.in);
       String st = s.nextLine();
       String t = s.nextLine();
       int count = 0, len =st.length();
       for(int i = 0;i < len; ++i) {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       }
       System.out.println(count);
   } main {
       Scanner s= new Scanner(System.in);
       String st = s.nextLine();
       String t = s.nextLine();
       int count = 0, len =st.length();
       for(int i = 0;i < len; ++i) {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       }
       System.out.println(count);
   } Scanner s= new Scanner(System.in); s new Scanner(System.in) String st = s.nextLine(); st s.nextLine() s.nextLine s String t = s.nextLine(); t s.nextLine() s.nextLine s int count = 0 count 0 len =st.length(); len st.length() st.length st for(int i = 0;i < len; ++i) {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       } int i = 0; int i = 0; i 0 i < len i len ++i ++i i {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       } {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       } if(st.charAt(i)!=t.charAt(i))
               count++; st.charAt(i)!=t.charAt(i) st.charAt(i) st.charAt st i t.charAt(i) t.charAt t i 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 s= new Scanner(System.in);
       String st = s.nextLine();
       String t = s.nextLine();
       int count = 0, len =st.length();
       for(int i = 0;i < len; ++i) {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       }
       System.out.println(count);
   }
} public class Main {
   public static void main(String[] args) {
       Scanner s= new Scanner(System.in);
       String st = s.nextLine();
       String t = s.nextLine();
       int count = 0, len =st.length();
       for(int i = 0;i < len; ++i) {
           if(st.charAt(i)!=t.charAt(i))
               count++;
       }
       System.out.println(count);
   }
} Main

import java.util.Scanner;

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