N,M = list(map(int,input().split()))
plant = []
for _ in range(N):
    a,b = list(map(int,input().split()))
    plant.append((M-a)//b)
plant.sort(reverse=True)

def check(n):
    now = plant[:]
    for i in range(N):
        if(now[-1] < i):return False
        for _ in range(n):
            if(not now):return True
            now.pop()
    return len(now) == 0

ng,ok = 0,N
while(ok - ng > 1):
    mid = (ok+ng)//2
    if(check(mid)):
        ok = mid
    else:
        ng = mid
print(ok)