N, H = map(int, input().split())
AB = [[int(i) for i in input().split()] for _ in range(N)]
A, B = map(list, zip(*AB))
B.sort()
X = max(A)
S = sum(B)

cnt = (H - S + X - 1) // X
H = H - X * cnt
for b in B[::-1]:
    H -= max(b, X)
    cnt += 1
    if H <= 0: break
print(cnt)
