N, H = map(int, input().split())
ls = []
for i in range(N):
  a, b = map(int, input().split())
  ls += [(a,-b)]
ls.sort(key=lambda x:x[0])
a = ls[-1][0]
ls.sort(key=lambda x:x[1])
ans = 0
for i in range(N-1):
  if ls[i][1]>=-a:
    break
  H += ls[i][1]
  ans += 1
  if H<=0:
    print(ans)
    break
else:
  n = H//a if H%a==0 else H//a+1
  ans += n
  print(ans)