import java.util.*;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a=0,z=0;
		char A = 'A';
		char Z = 'Z';
		String s = sc.next();
		char sa[] = s.toCharArray();
		for(int i=0;i<sa.length;i++) {
			if(sa[i]==A) {
				a=i;
				break;
			}
		}
		for(int i=sa.length-1;i>0;i--) {
			if(sa[i]==Z) {
				z=i;
				break;
			}
		}
		System.out.print(z-a+1);
		sc.close();
	}
}

/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