import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author HussienMoustafa
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BMinorChange solver = new BMinorChange();
        solver.solve(1, in, out);
        out.close();
    }

    static class BMinorChange {
        public void solve(int testNumber, Scanner s, PrintWriter sout) {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        }

    }

    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.StringTokenizer; StringTokenizer java.util import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.InputStream; InputStream java.io public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BMinorChange solver = new BMinorChange();
        solver.solve(1, in, out);
        out.close();
    }

    static class BMinorChange {
        public void solve(int testNumber, Scanner s, PrintWriter sout) {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        }

    }

    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BMinorChange solver = new BMinorChange();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BMinorChange solver = new BMinorChange();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) BMinorChange solver = new BMinorChange(); solver new BMinorChange() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class BMinorChange {
        public void solve(int testNumber, Scanner s, PrintWriter sout) {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        }

    } BMinorChange public void solve(int testNumber, Scanner s, PrintWriter sout) {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        } solve {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        } String word1 = s.next() word1 s.next() s.next s word2 = s.next(); word2 s.next() s.next s int cnt = 0; cnt 0 for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            } int i = 0; int i = 0; i 0 i < word1.length() i word1.length() word1.length word1 i++ i++ i {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            } {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            } if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++; i < word2.length() i word2.length() word2.length word2 {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } if (word1.charAt(i) != word2.charAt(i)) cnt++; word1.charAt(i) != word2.charAt(i) word1.charAt(i) word1.charAt word1 i word2.charAt(i) word2.charAt word2 i cnt++ cnt cnt++ cnt sout.println(cnt) sout.println sout cnt int testNumber testNumber Scanner s s PrintWriter sout sout static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

    } Scanner StringTokenizer st; st BufferedReader br; br public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        } Scanner {
            br = new BufferedReader(new InputStreamReader(s));
        } br = new BufferedReader(new InputStreamReader(s)) br new BufferedReader(new InputStreamReader(s)) InputStream s s public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        } next {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        } while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } st == null || !st.hasMoreTokens() st == null st null !st.hasMoreTokens() st.hasMoreTokens() st.hasMoreTokens st {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    st = new StringTokenizer(br.readLine());
                } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BMinorChange solver = new BMinorChange();
        solver.solve(1, in, out);
        out.close();
    }

    static class BMinorChange {
        public void solve(int testNumber, Scanner s, PrintWriter sout) {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        }

    }

    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BMinorChange solver = new BMinorChange();
        solver.solve(1, in, out);
        out.close();
    }

    static class BMinorChange {
        public void solve(int testNumber, Scanner s, PrintWriter sout) {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        }

    }

    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author HussienMoustafa
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BMinorChange solver = new BMinorChange();
        solver.solve(1, in, out);
        out.close();
    }

    static class BMinorChange {
        public void solve(int testNumber, Scanner s, PrintWriter sout) {
            String word1 = s.next(), word2 = s.next();
            int cnt = 0;
            for (int i = 0; i < word1.length(); i++) {
                if (i < word2.length()) {
                    if (word1.charAt(i) != word2.charAt(i)) cnt++;
                } else cnt++;
            }
            sout.println(cnt);
        }

    }

    static class Scanner {
        StringTokenizer st;
        BufferedReader br;

        public Scanner(InputStream s) {
            br = new BufferedReader(new InputStreamReader(s));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return st.nextToken();
        }

    }
}

