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())
target = max(A)
ans = 0
for i in B:
    if i >= target:
        H -= i
        ans += 1
print(ans-(-H//target))