n,W = map(int,input().split())
l = []
for _ in range(n):
    v,w = map(int,input().split())
    if w <= W:
        l.append((v,w))
n = len(l)
l.sort(key = lambda x:x[0] / x[1],reverse = True)

def kanwa(i,nowv,noww):
    flag = False
    for j in range(i,n):
        v,w = l[j]
        if w == W - noww:
            flag = True
        if w < W - noww:
            nowv += v
            noww += w
        else:
            rate = (W - noww) / w
            nowv += v * rate
            noww = W
            break
    return nowv,flag

import sys
sys.setrecursionlimit(10 ** 8)
zanteikai = 0
inf = 10 ** 18
def calc(i,nowv,noww):
    global zanteikai
    if i == n:
        if nowv > zanteikai:
            zanteikai = nowv
        return nowv
    kanwakai,flag = kanwa(i,nowv,noww)
    if flag:
        if kanwakai > zanteikai:
            zanteikai = kanwakai
        return int(kanwakai)
    if kanwakai < zanteikai:
        return -inf
    v,w = l[i]
    tmp = -inf
    if noww + w <= W:
        u = calc(i + 1,nowv + v,noww + w)
        if u > tmp:
            tmp = u
        if tmp > zanteikai:
            zanteikai = tmp
    u = calc(i + 1,nowv,noww)
    if u > tmp:
        tmp = u
    if tmp > zanteikai:
        zanteikai = tmp
    return tmp


now = 0
for v,w in l:
    if now + w <= W:
        now += w
        zanteikai += v
ans = calc(0,0,0)
print(ans)