write a code that keeps reading strings with a maximum length of $30$ characters each until the word "stop" is entered. then, the code prints the longest string that contains "najah". the code should ignore any word shorter than $5$ characters.

for example, if the input is:

student@najah.edu

najah$\_$street

najah$\_$hospital

nablus$\_$old$\_$city

palestine$\_$is$\_$my$\_$country

najah$\_$university

stop.

the output is:

student@najah.edu