Write a static method called bothstart that allows the user to input two strings and returns the string that is the longest substring s such that both inputs start with s.

for example,

bothstart( "radar dish", "radical food" ) returns "rad"

bothstart( "radar disk", "disk radar" ) returns ""

bothstart( "radar installation", "" ) returns ""

bothstart( "mendacious", "mendicant" ) returns "mend"

bothstart( "frankly", "frank" ) returns ""