import java.util.Scanner;

public class Main{
	public static void main(String[] args){
 		Scanner sc = new Scanner(System.in);
 		String s = sc.next();
 		char[] arr = s.toCharArray();
 		int count =0;
 		int idxA =0;
 		int idxZ =0;

 		for(int i=0; i<arr.length; i++){
 			if(arr[i] =='A'){
 				idxA = i;
 				break;
 			}
 		}
 		for(int j = s.length()-1; j>=0; j--){
 			if(arr[j] =='Z'){
 				idxZ = j;
 				break;
 			}
 		}
 		System.out.println(idxZ - idxA + 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