import java.util.Scanner;
public class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner(System.in);
        String s;
        int tmp_A,tmp_Z;
        tmp_A=0;
        tmp_Z=0;
        s=scan.next();
        tmp_A=0;
        for(int i =0;i<s.length();i++){
            if(s.charAt(i)=='A'){
                tmp_A=i;
                break;
            }
        }
        for(int i=s.length()-1;i>=0;i--){
            if(s.charAt(i)=='Z'){
                tmp_Z=i;
                break;
            }
        }
        System.out.println(tmp_Z-tmp_A+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