N, W = map(int, input().split()) 
VW = sorted([list(map(int, input().split())) for _ in range(N)], key=lambda x:x[0]/x[1], reverse=True)
SUM_V = [0 for _ in range(N)]
cur_sum = 0
for i in range(N - 1, -1, -1):
	cur_sum += VW[i][0]
	SUM_V[i] = cur_sum
ans = 0

def culc(cur_i, cur_v, cur_w):
	global ans
	ans = max(ans, cur_v)
	if cur_i == N or cur_v + SUM_V[cur_i] < ans:
		return
	i = cur_i
	v = cur_v
	w = cur_w
	while i < N and w + VW[i][1] < W:
		v += VW[i][0]
		w += VW[i][1]
	if v + VW[i][0] * (W - w) / VW[i][1] <= ans:
		return
	if cur_w + VW[cur_i][1] <= W:
		culc(cur_i + 1, cur_v + VW[cur_i][0], cur_w + VW[cur_i][1])
	culc(cur_i + 1, cur_v, cur_w)
culc(0, 0, 0)
print(ans)