N,M = map(int,input().split())
AB = [tuple(map(int,input().split())) for _ in range(N)]

C = [0--(M-a)//b for a,b in AB]
cc = [0] * (M+1)
for c in C:
    cc[c] += 1
cums = [0]
for a in cc:
    cums.append(cums[-1] + a)

ans = 0
for i in range(1,M+1):
    ans = max(ans, (0--cums[i+1]//i))
print(ans)