from collections import Counter

n, m = map(int, input().split())
items = [list(map(int, input().split())) for _ in range(n)]
a = []
for item in items:
    k = m-item[0]+1
    a.append(max(1, (k+item[1]-1)//item[1]))
l = 1
r = n
c = Counter(a)
keys = []
for x in c:
    keys.append(x)
keys.sort()
sm = 0
ans = 0
for x in keys:
    sm += c[x]
    ans = max(ans, (sm+x-1)//x)
print(ans)