import sys
read=sys.stdin.read

def main():
  n,h,*ab=map(int,read().split())
  sord=max(ab[0::2])
  tlst=[b>sord for b in ab[1::2]]
  thrownum=sum(tlst)
  h=h-sum(b*tf for b,tf in zip(ab[1::2],tlst))
  print(h//sord+(h%sord>0)+thrownum)

if __name__=='__main__':
  main()