import math
n,h=map(int,input().split())
a_max=0
b_=[]
for i in range(n):
    a,b=map(int,input().split())
    b_.append(b)
    if a_max<a:
        a_max=a
ans=0
for i in range(n):
    if a_max<b_[i]:
        ans+=1
        h-=b_[i]
print(ans+math.ceil(h/a_max))