N, H = map(int, input().split())
A = []
B = []
for _ in range(N):
    a, b = map(int, input().split())
    A.append(a)
    B.append(b)

Amax = max(A)
cnt = 0
for b in B:
    if Amax < b:
        H -= b
        cnt += 1
        if H < 0:
            print(cnt)
            exit()

print((H-1)//Amax+1 + cnt)