// This file is a "Hello, world!" in Java language by OpenJDK for wandbox.
import java.util.*;
import static java.lang.Integer.*;
import static java.lang.Long.*;
import static java.lang.Math.*;

class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
		char[] s = sc.next().toCharArray();
		sc.close();
        int ans=0;
        int aind=-1;
        int zind=-1;
        
        for (int i=0;i<s.length;i++){
            if (s[i]=='A' && aind==-1){
                aind=i;
            }    
            if (s[i]=='Z'){
                zind=i;
            }
        }
		System.out.println(zind-aind+1);        
    
    }
}


/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