N,H = map(int,input().split())
A = []; B = []
max_a = 0; cnt = 0

for i in range(N):
    a,b = map(int,input().split())
    if a > max_a:
        max_a = a
    B.append(b)

B.sort(reverse=True)

for b in B:
    if b > max_a:
        H -= b
        cnt += 1
    else:
        break
    if H <= 0:
        break

cnt += -(-H//max_a)
print(cnt)