import java.io.*;
import java.util.*;
public class Main {
	
	public static void main(String[] args) {
	
		MyScanner sc = new MyScanner();
		String s=sc.next();
		int l=s.length();
		int st=l-1;
		int en=0;
		for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		}
		
        System.out.println(en-st+1);
		
	}
	
	
	
	
//----------------------------------------------------------
	static int l_min(int[] a) {
		Arrays.sort(a);
		return a[0];
	}
	static int l_max(int[] a) {
		int l=a.length;
		Arrays.sort(a);
		return a[l-1];
	}
	public static PrintWriter out;

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}

	}
	

}


 import java.io.*; io.* java import java.util.*; util.* java public class Main {
	
	public static void main(String[] args) {
	
		MyScanner sc = new MyScanner();
		String s=sc.next();
		int l=s.length();
		int st=l-1;
		int en=0;
		for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		}
		
        System.out.println(en-st+1);
		
	}
	
	
	
	
//----------------------------------------------------------
	static int l_min(int[] a) {
		Arrays.sort(a);
		return a[0];
	}
	static int l_max(int[] a) {
		int l=a.length;
		Arrays.sort(a);
		return a[l-1];
	}
	public static PrintWriter out;

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}

	}
	

} Main public static PrintWriter out; out public static void main(String[] args) {
	
		MyScanner sc = new MyScanner();
		String s=sc.next();
		int l=s.length();
		int st=l-1;
		int en=0;
		for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		}
		
        System.out.println(en-st+1);
		
	} main {
	
		MyScanner sc = new MyScanner();
		String s=sc.next();
		int l=s.length();
		int st=l-1;
		int en=0;
		for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		}
		
        System.out.println(en-st+1);
		
	} MyScanner sc = new MyScanner(); sc new MyScanner() String s=sc.next(); s sc.next() sc.next sc int l=s.length(); l s.length() s.length s int st=l-1; st l-1 l 1 int en=0; en 0 for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		} int i=0; int i=0; i 0 i<l i l i++ i++ i {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		} {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		} if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			} s.charAt(i)=='A' s.charAt(i) s.charAt s i 'A' {
				st=Math.min(i,st);
			} st=Math.min(i,st) st Math.min(i,st) Math.min Math i st if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			} s.charAt(i)=='Z' s.charAt(i) s.charAt s i 'Z' {
				en=Math.max(i,en);
			} en=Math.max(i,en) en Math.max(i,en) Math.max Math i en System.out.println(en-st+1) System.out.println System.out System System.out en-st+1 en-st en st 1 String[] args args //----------------------------------------------------------
	static int l_min(int[] a) {
		Arrays.sort(a);
		return a[0];
	} l_min {
		Arrays.sort(a);
		return a[0];
	} Arrays.sort(a) Arrays.sort Arrays a return a[0]; a[0] a 0 int[] a a static int l_max(int[] a) {
		int l=a.length;
		Arrays.sort(a);
		return a[l-1];
	} l_max {
		int l=a.length;
		Arrays.sort(a);
		return a[l-1];
	} int l=a.length; l a.length a a.length Arrays.sort(a) Arrays.sort Arrays a return a[l-1]; a[l-1] a l-1 l 1 int[] a a public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}

	} MyScanner BufferedReader br; br StringTokenizer st; st public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		} MyScanner {
			br = new BufferedReader(new InputStreamReader(System.in));
		} br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		} next {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		} while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			} st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			} try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				} catch (IOException e) {
					e.printStackTrace();
				} IOException e {
					e.printStackTrace();
				} e.printStackTrace() e.printStackTrace e {
					st = new StringTokenizer(br.readLine());
				} st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
			return Integer.parseInt(next());
		} nextInt {
			return Integer.parseInt(next());
		} return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() {
			return Long.parseLong(next());
		} nextLong {
			return Long.parseLong(next());
		} return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() {
			return Double.parseDouble(next());
		} nextDouble {
			return Double.parseDouble(next());
		} return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		} nextLine {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		} String str = ""; str "" try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			} IOException e {
				e.printStackTrace();
			} e.printStackTrace() e.printStackTrace e {
				str = br.readLine();
			} str = br.readLine() str br.readLine() br.readLine br return str; str public class Main {
	
	public static void main(String[] args) {
	
		MyScanner sc = new MyScanner();
		String s=sc.next();
		int l=s.length();
		int st=l-1;
		int en=0;
		for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		}
		
        System.out.println(en-st+1);
		
	}
	
	
	
	
//----------------------------------------------------------
	static int l_min(int[] a) {
		Arrays.sort(a);
		return a[0];
	}
	static int l_max(int[] a) {
		int l=a.length;
		Arrays.sort(a);
		return a[l-1];
	}
	public static PrintWriter out;

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}

	}
	

} public class Main {
	
	public static void main(String[] args) {
	
		MyScanner sc = new MyScanner();
		String s=sc.next();
		int l=s.length();
		int st=l-1;
		int en=0;
		for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		}
		
        System.out.println(en-st+1);
		
	}
	
	
	
	
//----------------------------------------------------------
	static int l_min(int[] a) {
		Arrays.sort(a);
		return a[0];
	}
	static int l_max(int[] a) {
		int l=a.length;
		Arrays.sort(a);
		return a[l-1];
	}
	public static PrintWriter out;

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}

	}
	

} Main
import java.io.*;
import java.util.*;
public class Main {
	
	public static void main(String[] args) {
	
		MyScanner sc = new MyScanner();
		String s=sc.next();
		int l=s.length();
		int st=l-1;
		int en=0;
		for(int i=0;i<l;i++) {
			if(s.charAt(i)=='A') {
				st=Math.min(i,st);
			}
			if(s.charAt(i)=='Z') {
				en=Math.max(i,en);
			}
		}
		
        System.out.println(en-st+1);
		
	}
	
	
	
	
//----------------------------------------------------------
	static int l_min(int[] a) {
		Arrays.sort(a);
		return a[0];
	}
	static int l_max(int[] a) {
		int l=a.length;
		Arrays.sort(a);
		return a[l-1];
	}
	public static PrintWriter out;

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}

	}
	

}



