import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        char[] s= sc.next().toCharArray();
        int ans = 0;
        outloop:for(int i = 0;i<s.length;i++){
            if(s[i]=='A'){
                for(int j = i+1;j<s.length;j++){
                    if(s[j]=='Z'){
                        ans = j-i+1;
                    }
                }
                break outloop;
            }
        }
        System.out.println(ans);
    }
} import java.util.*; util.* java class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        char[] s= sc.next().toCharArray();
        int ans = 0;
        outloop:for(int i = 0;i<s.length;i++){
            if(s[i]=='A'){
                for(int j = i+1;j<s.length;j++){
                    if(s[j]=='Z'){
                        ans = j-i+1;
                    }
                }
                break outloop;
            }
        }
        System.out.println(ans);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        char[] s= sc.next().toCharArray();
        int ans = 0;
        outloop:for(int i = 0;i<s.length;i++){
            if(s[i]=='A'){
                for(int j = i+1;j<s.length;j++){
                    if(s[j]=='Z'){
                        ans = j-i+1;
                    }
                }
                break outloop;
            }
        }
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        char[] s= sc.next().toCharArray();
        int ans = 0;
        outloop:for(int i = 0;i<s.length;i++){
            if(s[i]=='A'){
                for(int j = i+1;j<s.length;j++){
                    if(s[j]=='Z'){
                        ans = j-i+1;
                    }
                }
                break outloop;
            }
        }
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) char[] s= sc.next().toCharArray(); s sc.next().toCharArray() sc.next().toCharArray sc.next() sc.next sc int ans = 0; ans 0 System.out.println(ans) System.out.println System.out System System.out ans String[] args args
import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        char[] s= sc.next().toCharArray();
        int ans = 0;
        outloop:for(int i = 0;i<s.length;i++){
            if(s[i]=='A'){
                for(int j = i+1;j<s.length;j++){
                    if(s[j]=='Z'){
                        ans = j-i+1;
                    }
                }
                break outloop;
            }
        }
        System.out.println(ans);
    }
}