import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
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);
        AtCoder solver = new AtCoder();
        solver.solve(1, in, out);
        out.close();
    }

    static class AtCoder {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        }

    }
}
 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.Scanner; Scanner java.util 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);
        AtCoder solver = new AtCoder();
        solver.solve(1, in, out);
        out.close();
    }

    static class AtCoder {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        }

    }
} 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);
        AtCoder solver = new AtCoder();
        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);
        AtCoder solver = new AtCoder();
        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) AtCoder solver = new AtCoder(); solver new AtCoder() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class AtCoder {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        }

    } AtCoder public void solve(int testNumber, Scanner in, PrintWriter out) {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        } solve {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        } String s = in.nextLine(); s in.nextLine() in.nextLine in int left = s.indexOf("A"); left s.indexOf("A") s.indexOf s "A" int right = s.lastIndexOf("Z"); right s.lastIndexOf("Z") s.lastIndexOf s "Z" out.println(right - left + 1) out.println out right - left + 1 right - left right left 1 int testNumber testNumber Scanner in in PrintWriter out out 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);
        AtCoder solver = new AtCoder();
        solver.solve(1, in, out);
        out.close();
    }

    static class AtCoder {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        }

    }
} 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);
        AtCoder solver = new AtCoder();
        solver.solve(1, in, out);
        out.close();
    }

    static class AtCoder {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
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);
        AtCoder solver = new AtCoder();
        solver.solve(1, in, out);
        out.close();
    }

    static class AtCoder {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            String s = in.nextLine();
            int left = s.indexOf("A");
            int right = s.lastIndexOf("Z");

            out.println(right - left + 1);
        }

    }
}

