$ echo 'Global symbol "$input" requires explicit package name at -e line 1.' | splain
Global symbol "$input" requires explicit package name at -e line 1 (#1)
    (F) You've said "use strict" or "use strict vars", which indicates 
    that all variables must either be lexically scoped (using "my" or "state"), 
    declared beforehand using "our", or explicitly qualified to say 
    which package the global variable is in (using "::").