import math

count = 0
N, H = list(map(int, input().split()))
ab = []

for i in range(N):
    ab.append(list(map(int, input().split())))

max_ab = max(ab)
for i in range(N):
    if max_ab[0] <= ab[i][1]:
        H -= ab[i][1]
        count += 1

if H > 0:
    count += math.ceil(H / max_ab[0])

print(count)