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

public class Main { // "Main" should be used for most online judges
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String str = sc.nextLine();
		int index = str.indexOf('A');
		int count = 1;
		for (int i = index; i < str.length(); i++ )
		{
			if(str.charAt(i)=='Z')
			{
				count = i -index +1;

			}
		}
		System.out.print(count);
	}
}
/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