import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
	String s=sc.nextLine();
	char c[]=s.toCharArray();
int a=0;
int b=0;
	for(int i=0;i<s.length();i++){
		if(c[i]=='A'){
			a=i;
			break;
		}
	}
	for(int i=s.length()-1;i>0;i--){
		if(c[i]=='Z'){
			b=i;
			break;
		}
	}
System.out.println(b-a+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