import java.io.*;
import java.util.*;

public class Main{

	static class FastReader{
		BufferedReader br;
		StringTokenizer st;
		public FastReader(){
			br = new BufferedReader(new InputStreamReader(System.in));
		}
		public String next(){
			try{
				while(st==null||!st.hasMoreElements()){
					st = new StringTokenizer(br.readLine());
				}
			}catch(Exception e){
				e.printStackTrace();
			}
			return st.nextToken();
	
		}
		public int nextInt(){
			return Integer.parseInt(next());
		}
		public long nextLong(){
			return Long.parseLong(next());
		}
		public double nextDouble(){
			return Double.parseDouble(next());
		}
		public String nextLine(){
			String s = "";
			try{
				s = br.readLine();
			}catch(Exception e){
				e.printStackTrace();
			}	
			return s;		
		}
	} 
	
	public static void main(String[] args){
		FastReader in = new FastReader();
		PrintWriter out = new PrintWriter(System.out);
		char[] s = in.next().toCharArray();
		int start = -1;
		boolean done = false;
		int end = -1;
		for(int i = 0; i < s.length; i++){
			if(!done&&s[i] == 'A'){
				start = i;
				done = true;
			}
			else if (s[i]=='Z'){
				end = i;
			}
		}
		int len = end - start +1;
		out.println(len);	
		out.flush();
		out.close();  
	}

}




/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz