import Data.List (isInfixOf)

pattern = "toast"

format number line = show number ++ ":" ++ line
    
grep number input
    = if null input
      then []
      else if isInfixOf pattern (head input)
           then   format number (head input)
                : grep (number + 1) (tail input)
           else   grep (number + 1) (tail input)

grepFromOne input = unlines (grep 1 (lines input))

main = interact grepFromOne