def ceildiv(a: int, b: int) -> int:
    return (a + b - 1) // b


INF = 1 << 62
N, M = map(int, input().split())
xs = []
for _ in range(N):
    a, b = map(int, input().split())
    xs.append((a, b))

ys = sorted([ceildiv(M-a+1, b) for a, b in xs])

ans = max(i // y + 1 for i, y in enumerate(ys))
print(ans)