import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.PriorityQueue;
import java.util.Scanner;

class Main {
    static final int MOD = 1000000007;
    static final int INF = 1 << 30;

    Main() {
        Scanner sc = new Scanner(System.in);
        long ans = 0;
        String S = sc.next();
        System.out.println(S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length());
    }

    public static void main(String[] args) {
        new Main();
    }
} import java.util.ArrayList; ArrayList java.util import java.util.Arrays; Arrays java.util import java.util.Collections; Collections java.util import java.util.Comparator; Comparator java.util import java.util.HashMap; HashMap java.util import java.util.HashSet; HashSet java.util import java.util.Iterator; Iterator java.util import java.util.List; List java.util import java.util.Map.Entry; Entry java.util.Map import java.util.PriorityQueue; PriorityQueue java.util import java.util.Scanner; Scanner java.util class Main {
    static final int MOD = 1000000007;
    static final int INF = 1 << 30;

    Main() {
        Scanner sc = new Scanner(System.in);
        long ans = 0;
        String S = sc.next();
        System.out.println(S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length());
    }

    public static void main(String[] args) {
        new Main();
    }
} Main static final int MOD = 1000000007; MOD 1000000007 static final int INF = 1 << 30; INF 1 << 30 1 30 Main() {
        Scanner sc = new Scanner(System.in);
        long ans = 0;
        String S = sc.next();
        System.out.println(S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length());
    } Main {
        Scanner sc = new Scanner(System.in);
        long ans = 0;
        String S = sc.next();
        System.out.println(S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long ans = 0; ans 0 String S = sc.next(); S sc.next() sc.next sc System.out.println(S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length()) System.out.println System.out System System.out S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length() S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1) S.substring S S.indexOf('A') S.indexOf S 'A' S.lastIndexOf('Z')+1 S.lastIndexOf('Z') S.lastIndexOf S 'Z' 1 public static void main(String[] args) {
        new Main();
    } main {
        new Main();
    } new Main() String[] args args
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.PriorityQueue;
import java.util.Scanner;

class Main {
    static final int MOD = 1000000007;
    static final int INF = 1 << 30;

    Main() {
        Scanner sc = new Scanner(System.in);
        long ans = 0;
        String S = sc.next();
        System.out.println(S.substring(S.indexOf('A'), S.lastIndexOf('Z')+1).length());
    }

    public static void main(String[] args) {
        new Main();
    }
}
