from math import ceil

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())

a = max(a)
b.sort(reverse=True)

ans = 0
atk = 0
for i in range(N):
  if a >= b[i] or atk >= H:
    break
  ans += 1
  atk += b[i]

if atk < H:
  ans += ceil((H - atk) / a)

print(ans)
