import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        String s = sc.next();
        int l = s.length();
        String a = "AZ";
        int x = 0;
        int y = 0;

        for(int i=0; i<l; i++){
            if(s.charAt(i)==a.charAt(0)){
                x = i;
                break;
            }
        }
        for(int i=l-1; i>=0; i--){
            if(s.charAt(i)==a.charAt(1)){
                y = i;
                break;
            }
        }
        System.out.println(y - x + 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