N, H = map(int, input().split())
A = 0
B = [0] * (N + 1)
for i in range(N):
  a, b = map(int, input().split())
  A = max(a, A)
  B[i] = b
B.sort(reverse=True)
cnt = 0
i  = 0
while H > 0:
  if B[i] > A:
    H -= B[i]
    cnt += 1
    i += 1
  else:
    k = -(-H // A)
    H -= A * k
    cnt += k
print(cnt)