n, h = map(int, input().split())
A, B = [0]*n, [0]*n
for i in range(n):
  A[i], B[i] = map(int, input().split())
maxa = max(A)
c, d = 0, 0
for i in range(n):
  if B[i] > maxa:
    c += B[i]
    d += 1
    if c >= h:
      print(d)
      exit()
ans = d - (c-h)//maxa
print(ans)