import sequtils
template times*(n:int,body) = (for _ in 0..<n: body)

proc getchar_unlocked():char {. importc:"getchar_unlocked",header: "<stdio.h>" .}
proc scan(): int =
  while true:
    let k = getchar_unlocked()
    if k < '0': break
    result = 10 * result + k.ord - '0'.ord

let n = scan()
var V = newSeq[int](n)
scan().times:
  let a = scan()
  let b = scan()
  V[a] += 1
  V[b] += 1

var oddCount = 0
for v in V:
  if v mod 2 == 1:
    oddCount += 1
    if oddCount > 2 :
      quit "NO",0
echo "YES"