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]
C.sort()

def is_ok(k):
    if k==0: return False
    for i in range(N):
        j = i//k + 1
        if j > C[i]:
            return False
    return True

ok = M
ng = 0
while ok-ng > 1:
    m = (ok+ng)//2
    if is_ok(m):
        ok = m
    else:
        ng = m
print(ok)