import java.util.*;

class Main {
public static void main(String[] args){

Scanner sc = new Scanner(System.in);
String s = sc.next();
int length = s.length();
int a = length;
int z = -1;
String ss;
for(int i = 0;i < length ;i++){
  ss = s.substring(i,i+1);
  if(ss.equals("A") && a > i){
    a = i;
  }else if(ss.equals("Z") && z < i){
    z = i;
  }
}
int ans = z - a + 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