import java.util.*;

public class Main {
	
	
	public static int MinorChange(String s ,String t) {
		int count = 0;
		
		 char[] arr1 = s.toCharArray();
		 char[] arr2 = t.toCharArray();
//		 
//		 Arrays.sort(arr1);
//		 Arrays.sort(arr2);
		for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		}
		
		return count;
	}

	public static void main(String[] args) {
		Scanner s1 = new Scanner (System.in); 
		String s =s1.next();
		String t = s1.next();
		System.out.println(MinorChange(s, t));
		

	}

} import java.util.*; util.* java public class Main {
	
	
	public static int MinorChange(String s ,String t) {
		int count = 0;
		
		 char[] arr1 = s.toCharArray();
		 char[] arr2 = t.toCharArray();
//		 
//		 Arrays.sort(arr1);
//		 Arrays.sort(arr2);
		for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		}
		
		return count;
	}

	public static void main(String[] args) {
		Scanner s1 = new Scanner (System.in); 
		String s =s1.next();
		String t = s1.next();
		System.out.println(MinorChange(s, t));
		

	}

} Main public static int MinorChange(String s ,String t) {
		int count = 0;
		
		 char[] arr1 = s.toCharArray();
		 char[] arr2 = t.toCharArray();
//		 
//		 Arrays.sort(arr1);
//		 Arrays.sort(arr2);
		for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		}
		
		return count;
	} MinorChange {
		int count = 0;
		
		 char[] arr1 = s.toCharArray();
		 char[] arr2 = t.toCharArray();
//		 
//		 Arrays.sort(arr1);
//		 Arrays.sort(arr2);
		for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		}
		
		return count;
	} int count = 0; count 0 char[] arr1 = s.toCharArray(); arr1 s.toCharArray() s.toCharArray s char[] arr2 = t.toCharArray(); arr2 t.toCharArray() t.toCharArray t for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		} int i=0,j=0; int i=0 i 0 j=0; j 0 i<s.length() i s.length() s.length s i++,j++ i++ i j++ j {
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		} {
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		} if(arr1[i]!=arr2[j]) {
				count++;
			} arr1[i]!=arr2[j] arr1[i] arr1 i arr2[j] arr2 j {
				count++;
			} count++ count return count; count String s s String t t public static void main(String[] args) {
		Scanner s1 = new Scanner (System.in); 
		String s =s1.next();
		String t = s1.next();
		System.out.println(MinorChange(s, t));
		

	} main {
		Scanner s1 = new Scanner (System.in); 
		String s =s1.next();
		String t = s1.next();
		System.out.println(MinorChange(s, t));
		

	} Scanner s1 = new Scanner (System.in); s1 new Scanner (System.in) String s =s1.next(); s s1.next() s1.next s1 String t = s1.next(); t s1.next() s1.next s1 System.out.println(MinorChange(s, t)) System.out.println System.out System System.out MinorChange(s, t) MinorChange s t String[] args args public class Main {
	
	
	public static int MinorChange(String s ,String t) {
		int count = 0;
		
		 char[] arr1 = s.toCharArray();
		 char[] arr2 = t.toCharArray();
//		 
//		 Arrays.sort(arr1);
//		 Arrays.sort(arr2);
		for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		}
		
		return count;
	}

	public static void main(String[] args) {
		Scanner s1 = new Scanner (System.in); 
		String s =s1.next();
		String t = s1.next();
		System.out.println(MinorChange(s, t));
		

	}

} public class Main {
	
	
	public static int MinorChange(String s ,String t) {
		int count = 0;
		
		 char[] arr1 = s.toCharArray();
		 char[] arr2 = t.toCharArray();
//		 
//		 Arrays.sort(arr1);
//		 Arrays.sort(arr2);
		for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		}
		
		return count;
	}

	public static void main(String[] args) {
		Scanner s1 = new Scanner (System.in); 
		String s =s1.next();
		String t = s1.next();
		System.out.println(MinorChange(s, t));
		

	}

} Main
import java.util.*;

public class Main {
	
	
	public static int MinorChange(String s ,String t) {
		int count = 0;
		
		 char[] arr1 = s.toCharArray();
		 char[] arr2 = t.toCharArray();
//		 
//		 Arrays.sort(arr1);
//		 Arrays.sort(arr2);
		for(int i=0,j=0;i<s.length();i++,j++)
		{
			if(arr1[i]!=arr2[j]) {
				count++;
			}
		}
		
		return count;
	}

	public static void main(String[] args) {
		Scanner s1 = new Scanner (System.in); 
		String s =s1.next();
		String t = s1.next();
		System.out.println(MinorChange(s, t));
		

	}

}
