N,M = map(int, input().split())
D = []
for _ in range(N):
    a,b = map(int, input().split())
    D.append((M-a)//b)
D = sorted(D)
low = 0
high = N
while high-low>1:
    mid = (low+high)//2
    cnt = 1
    flag = True
    for i in range(mid,N,mid):
        if D[i]-cnt>=0:
            cnt += 1
        else:
            flag = False
            break
    if flag:
        high = mid
    else:
        low = mid
print(high)