from bisect import bisect
from collections import defaultdict
from itertools import accumulate
def solve(n, W, vw):
    vw.sort(key=lambda x: x[0] / x[1], reverse=True)
    vs = []
    ws = []
    wei_to_val = defaultdict(int)
    wei_to_val[0] = 0
    for v, w in vw:
        vs.append(v)
        ws.append(w)
    cum_v, cum_w = [0] + list(accumulate(vs)), [0] + list(accumulate(ws))
    cum_v.append(cum_v[-1])
    res = cum_v[bisect(cum_w, W) - 1]
    for i, (v, w) in enumerate(vw):
        cur_w = W + cum_w[i]
        del_v = cum_v[i]
        for w2, v2 in list(wei_to_val.items()):
            if w2 + w > W: continue
            j = bisect(cum_w, cur_w - w2) - 1
            tmp_ans = v2 + cum_v[j] - del_v
            if j < n - 1:
                plus = vs[j] * (cur_w - w2 - cum_w[j]) / ws[j]
            else:
                plus = 0
            if tmp_ans + plus <= res:
                del wei_to_val[w2]
                continue
            res = max(res, tmp_ans)
            wei_to_val[w2 + w] = max(wei_to_val[w2 + w], v2 + v)
    return res
n, W = map(int, input().split())
vw = [list(map(int, input().split())) for i in range(n)]
print(solve(n, W, vw))