N, H = [int(i) for i in input().split()]
ken_a = 0
ken_b = []
for _ in range(N):
    a,b = input().split()
    if ken_a < int(a):
        ken_a = int(a)
    ken_b.append(int(b))
res = 0
for b_ in ken_b:
    if b_ > ken_a:
        H = H - b_
        res += 1

res = res + (H//ken_a)
# if H%ken_a != 0:
#     res += 1
print(res)