import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String ns = sc.next();
    String[] s = ns.split("");
    int start = 0;
    int end = 0;
    for (int i = 0; i < s.length; i++) {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    }
    for (int i = s.length - 1; i >= 0; i--) {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    }
    System.out.println(end - start + 1);
  }
} import java.util.*; util.* java class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String ns = sc.next();
    String[] s = ns.split("");
    int start = 0;
    int end = 0;
    for (int i = 0; i < s.length; i++) {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    }
    for (int i = s.length - 1; i >= 0; i--) {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    }
    System.out.println(end - start + 1);
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String ns = sc.next();
    String[] s = ns.split("");
    int start = 0;
    int end = 0;
    for (int i = 0; i < s.length; i++) {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    }
    for (int i = s.length - 1; i >= 0; i--) {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    }
    System.out.println(end - start + 1);
  } main {
    Scanner sc = new Scanner(System.in);
    String ns = sc.next();
    String[] s = ns.split("");
    int start = 0;
    int end = 0;
    for (int i = 0; i < s.length; i++) {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    }
    for (int i = s.length - 1; i >= 0; i--) {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    }
    System.out.println(end - start + 1);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String ns = sc.next(); ns sc.next() sc.next sc String[] s = ns.split(""); s ns.split("") ns.split ns "" int start = 0; start 0 int end = 0; end 0 for (int i = 0; i < s.length; i++) {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    } int i = 0; int i = 0; i 0 i < s.length i s.length s s.length i++ i++ i {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    } {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    } if (s[i].equals("A")) {
        start = i;
        break;
      } s[i].equals("A") s[i].equals s[i] s i "A" {
        start = i;
        break;
      } start = i start i break; for (int i = s.length - 1; i >= 0; i--) {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    } int i = s.length - 1; int i = s.length - 1; i s.length - 1 s.length s s.length 1 i >= 0 i 0 i-- i-- i {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    } {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    } if (s[i].equals("Z")) {
        end = i;
        break;
      } s[i].equals("Z") s[i].equals s[i] s i "Z" {
        end = i;
        break;
      } end = i end i break; System.out.println(end - start + 1) System.out.println System.out System System.out end - start + 1 end - start end start 1 String[] args args
import java.util.*;

class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String ns = sc.next();
    String[] s = ns.split("");
    int start = 0;
    int end = 0;
    for (int i = 0; i < s.length; i++) {
      if (s[i].equals("A")) {
        start = i;
        break;
      }
    }
    for (int i = s.length - 1; i >= 0; i--) {
      if (s[i].equals("Z")) {
        end = i;
        break;
      }
    }
    System.out.println(end - start + 1);
  }
}