import times, strutils, sequtils, math, algorithm, tables, sets, lists, intsets
import critbits, future, strformat, deques,heapqueue
template `max=`(x,y) = x = max(x,y)
template `min=`(x,y) = x = min(x,y)
template `mod=`(x,y) = x = x mod y
template scan2 = (scan(), scan())
template scan3 = (scan(), scan())
let read* = iterator: string {.closure.} =
    while true: (for s in stdin.readLine.split: yield s)
proc scan(): int = read().parseInt
proc scanf(): float = read().parseFloat
proc toInt(c:char): int =
  return int(c) - int('0')




proc solve():int=
  var 
    n = scan()
    x = scan()
    aseq = newseqwith(n,scan()-x)
    bseq = newseqwith(n,scan())
  if aseq.sum()>=0:
    return 0
  else:
    if aseq.filterIt(it>=0).len==0:
      return -1
    var 
      ma = newseq[int]()
      mb = newseq[int]()
      goal = -aseq.sum()
      mx = 500*100
    for i in 0..<n:
      if aseq[i]<0:
        ma.add(-aseq[i])
        mb.add(bseq[i])
    var
      #dp[i][j] := i個目まで見てj点プラスするのに必要な最小コスト
      dp = newseqwith(ma.len+1,newseqwith(mx+1,int.high.div(4)))
    result = int.high.div(4)
    dp[0][0]=0
    for i in 1..ma.len:
      for j in 0..mx:
        if j-ma[i-1]>=0:
          dp[i][j] = min(dp[i-1][j], dp[i-1][j-ma[i-1]]+mb[i-1])
        else:
          dp[i][j].min=dp[i-1][j]
        if j>=goal:
          result.min=dp[i][j]


        

  
  

echo solve()