n,h,*ab = map(int,open(0).read().split())
a_max = max(ab[::2])
b_sort = sorted(ab[1::2],reverse = True)

ans = 0
i = 0
while h>0:
    if i<n and b_sort[i] > a_max:
        h -= b_sort[i]
        i += 1
        ans += 1
    else:
        ans += -(-h//a_max)
        h = 0
print(ans)
    