from collections import Counter

n,m=map(int,input().split())
cnt=Counter()
for _ in range(n):
    a,b=map(int,input().split())
    d=(m-a)//b+1
    cnt[d]+=1
ans=0
s=0
for d in sorted(cnt):
    s+=cnt[d]
    ans=max(ans,(s+d-1)//d)
print(ans)