import java.util.Scanner;

class Main{
	public static void main(String[] args){
		
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		String a = "A";
		String z = "Z";
		int ans1 = 0;
		int ans2 = 0;
		int flag1 = 0;
		int flag2 = 0;

		sc.close();

		for(int i=0; i<s.length(); i++){
			if(flag1==0){
				if(a.equals(String.valueOf(s.charAt(i)))){
					ans1 = i;
					flag1 = 1;
				}
			}
		}

		for(int i=(s.length()-1); i>=0; i--){
			if(flag2==0){
				if(z.equals(String.valueOf(s.charAt(i)))){
					ans2 = i;
					flag2 = 1;
				}
			}
		}

		System.out.println(ans2-ans1+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