import java.util.*;
import static java.lang.System.*;
public class Main {
public static void main(String[] args){
Scanner sc = new Scanner(in);
String s=sc.next();
int l=0,r=0;
    for (int i = 0; i < s.length(); i++) {
        if(s.charAt(i)=='A'){l=i;break;}
    }
    for (int i = s.length()-1; i >=0; i--) {
        if(s.charAt(i)=='Z'){r=i+1;break;}
    }
    out.println(s.substring(l,r).length());
}}
/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