import java.util.*;

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

        String s = sc.next();

        int iA = 0;
        while(s.charAt(iA) != 'A'){
            ++iA;
        }
        
        int iZ = s.length()-1;
        while(s.charAt(iZ) != 'Z'){
            --iZ;
        }

        int ans = iZ - iA + 1;

        System.out.println(ans);
    }
}


/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