import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    String T = sc.next();

    char[] cS = S.toCharArray();
    char[] cT = T.toCharArray();

    int ans = 0;

    for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    }
    System.out.println(ans);
  }
} import java.util.Scanner; Scanner java.util public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    String T = sc.next();

    char[] cS = S.toCharArray();
    char[] cT = T.toCharArray();

    int ans = 0;

    for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    }
    System.out.println(ans);
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    String T = sc.next();

    char[] cS = S.toCharArray();
    char[] cT = T.toCharArray();

    int ans = 0;

    for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    }
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    String T = sc.next();

    char[] cS = S.toCharArray();
    char[] cT = T.toCharArray();

    int ans = 0;

    for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    }
    System.out.println(ans);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String S = sc.next(); S sc.next() sc.next sc String T = sc.next(); T sc.next() sc.next sc char[] cS = S.toCharArray(); cS S.toCharArray() S.toCharArray S char[] cT = T.toCharArray(); cT T.toCharArray() T.toCharArray T int ans = 0; ans 0 for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    } int i = 0; int i = 0; i 0 i < S.length() i S.length() S.length S i++ i++ i {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    } {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    } if(cS == cT) {
    		System.out.println(ans);
    		return;
    	} cS == cT cS cT {
    		System.out.println(ans);
    		return;
    	} System.out.println(ans) System.out.println System.out System System.out ans return; if(cS[i] != cT[i]) {
    		ans++;
    	} cS[i] != cT[i] cS[i] cS i cT[i] cT i {
    		ans++;
    	} ans++ ans System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    String T = sc.next();

    char[] cS = S.toCharArray();
    char[] cT = T.toCharArray();

    int ans = 0;

    for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    }
    System.out.println(ans);
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    String T = sc.next();

    char[] cS = S.toCharArray();
    char[] cT = T.toCharArray();

    int ans = 0;

    for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    }
    System.out.println(ans);
  }
} Main
import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String S = sc.next();
    String T = sc.next();

    char[] cS = S.toCharArray();
    char[] cT = T.toCharArray();

    int ans = 0;

    for(int i = 0; i < S.length(); i++) {
    	if(cS == cT) {
    		System.out.println(ans);
    		return;
    	}
      	if(cS[i] != cT[i]) {
    		ans++;
    	}
    }
    System.out.println(ans);
  }
}