N, H = map(int, input().split())
a = [0] * N
b = [0] * N
for i in range(N):
    a[i], b[i] = map(int, input().split())

a_max = max(a)
c = 0
for i in range(N):
    if b[i] > a_max and H > 0:
        H -= b[i]
        c += 1

if H > 0:
    c += (H + a_max - 1) // a_max

print(c)
