N, H = map(int,raw_input().split())
a = []
b = []
for i in range(N):
    ai, bi = map(int,raw_input().split())
    a.append(ai)
    b.append(bi)

a_max = max(a)
b = sorted(b)


ans = 0
for i in reversed(range(N)):
    if b[i] >= a_max:
        ans = ans + 1
        H = H - b[i]
    if H < 0:
        break

ans = ans + -(-H//a_max)

print ans


