fun readInt () =
    valOf (TextIO.scanStream (Int.scan StringCvt.DEC) TextIO.stdIn)


fun readStr () =
    let
        fun scan reader stream = SOME (StringCvt.splitl (not o Char.isSpace) reader (StringCvt.skipWS reader stream))
    in
        valOf (TextIO.scanStream scan TextIO.stdIn)
    end


fun isExistLOVE nil = false
  | isExistLOVE (#"L" :: #"O" :: #"V" :: #"E" :: _) = true
  | isExistLOVE (h :: tl) =  isExistLOVE tl


fun findAns nil = "NO"
  | findAns (h :: tl) =
    if isExistLOVE (String.explode h) then "YES"
    else findAns tl


val () =
    let
        val n = readInt ()
        val m = readInt ()
        val s_s = List.tabulate (n, fn _ => readStr ())

        val ans = findAns s_s
    in
        print (ans ^ "\n")  
    end