import java.util.*;

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

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