n,m=map(int,input().split())
d=[]
for i in range(n):
  a,b=map(int,input().split())
  c=(m-a)//b
  d+=[c]
d.sort()
ok=n
ng=0
while ok-ng>1:
  m=(ok+ng)//2
  if all(i//m<=d[i] for i in range(n)):
    ok=m
  else:
    ng=m
print(ok)