import java.util.*;
public class Main{
  public static void main(String[] arg) {

		Scanner sc = new Scanner(System.in);//文字の入力
		String S = sc.next();
		String T = sc.next();
		int count = S.length();//何文字かをcountに代入

		for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		}
		System.out.println(count);
	}
} import java.util.*; util.* java public class Main{
  public static void main(String[] arg) {

		Scanner sc = new Scanner(System.in);//文字の入力
		String S = sc.next();
		String T = sc.next();
		int count = S.length();//何文字かをcountに代入

		for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		}
		System.out.println(count);
	}
} Main public static void main(String[] arg) {

		Scanner sc = new Scanner(System.in);//文字の入力
		String S = sc.next();
		String T = sc.next();
		int count = S.length();//何文字かをcountに代入

		for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		}
		System.out.println(count);
	} main {

		Scanner sc = new Scanner(System.in);//文字の入力
		String S = sc.next();
		String T = sc.next();
		int count = S.length();//何文字かをcountに代入

		for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		}
		System.out.println(count);
	} 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 int count = S.length(); count S.length() S.length S for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		} int i = 0; int i = 0; i 0 i < S.length() i S.length() S.length S i++ i++ i {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		} {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		} if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			} Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1)) Objects.equals Objects S.substring(i, i + 1) S.substring S i i + 1 i 1 T.substring(i, i + 1) T.substring T i i + 1 i 1 {
				count -= 1;
			} count -= 1 count 1 System.out.println(count) System.out.println System.out System System.out count String[] arg arg public class Main{
  public static void main(String[] arg) {

		Scanner sc = new Scanner(System.in);//文字の入力
		String S = sc.next();
		String T = sc.next();
		int count = S.length();//何文字かをcountに代入

		for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		}
		System.out.println(count);
	}
} public class Main{
  public static void main(String[] arg) {

		Scanner sc = new Scanner(System.in);//文字の入力
		String S = sc.next();
		String T = sc.next();
		int count = S.length();//何文字かをcountに代入

		for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		}
		System.out.println(count);
	}
} Main
import java.util.*;
public class Main{
  public static void main(String[] arg) {

		Scanner sc = new Scanner(System.in);//文字の入力
		String S = sc.next();
		String T = sc.next();
		int count = S.length();//何文字かをcountに代入

		for (int i = 0; i < S.length(); i++) {
			//Objects.equals(a,b);で文字列の比較
			if (Objects.equals(S.substring(i, i + 1), T.substring(i, i + 1))) {
				count -= 1;
			}
		}
		System.out.println(count);
	}
}