import math
N,H = map(int,input().split())
a,b = [],[]
for i in range(N):
    k,kk = map(int,input().split())
    a.append(k)
    b.append(kk)

zanmax = max(a)

num = 0
cnt = 0
for i in b:
    if zanmax <= i:
        num += i
        cnt += 1
    if num >= H:
        print(cnt)
        exit()

cnt += int(math.ceil(((H - num)/zanmax)))
print(cnt)
