You have N items that you want to put them into a knapsack. Item i has value vi and weight wi.

You want to find a subset of items to put such that:

* The total value of the items is as large as possible.
* The items have combined weight at most W, that is capacity of the knapsack.



Find the maximum total value of items in the knapsack.

Constraints

* 1 ≤ N ≤ 40
* 1 ≤ vi ≤ 1015
* 1 ≤ wi ≤ 1015
* 1 ≤ W ≤ 1015

Input


N W
v1 w1
v2 w2
:
vN wN


The first line consists of the integers N and W. In the following N lines, the value and weight of the i-th item are given.

Output

Print the maximum total values of the items in a line.

Examples

Input

4 5
4 2
5 2
2 1
8 3


Output

13


Input

2 20
5 9
4 10


Output

9
#include "bits/stdc++.h"

using namespace std;

//------------------------------- Libraries --------------------------------//

//------------------------------- Type Names -------------------------------//

using i64 = int_fast64_t;

using seika = string;
//akari : 1D, yukari : 2D, maki : 3D vector
template <class kizuna>
using akari = vector<kizuna>;
template <class yuzuki>
using yukari = akari<akari<yuzuki>>;
template <class tsurumaki>
using maki = akari<yukari<tsurumaki>>;
//akane : ascending order, aoi : decending order
template <class kotonoha>
using akane = priority_queue<kotonoha, akari<kotonoha>, greater<kotonoha>>;
template <class kotonoha>
using aoi = priority_queue<kotonoha>;

//------------------------------- Dubug Functions ---------------------------//
inline void print()
{
    cout << endl;
}
template <typename First, typename... Rest>
void print(const First &first, const Rest &... rest)
{
    cout << first << ' ';
    print(rest...);
}
//------------------------------- Solver ------------------------------------//

void solve()
{
    int n;
    i64 w;
    cin >> n >> w;
    int ofs = n / 2, res = n - ofs;
    akari<i64> vs(n), ws(n);
    akari<pair<i64, i64>> xs, ys;
    for (int i = 0; i < n; i++)
    {
        cin >> vs[i] >> ws[i];
    }
    for (int i = 0; i < 1 << ofs; i++)
    {
        i64 wsum = 0, vsum = 0;
        for (int j = 0; j < ofs; j++)
        {
            if (i >> j & 1)
            {
                wsum += ws[j];
                vsum += vs[j];
            }
        }
        if (wsum <= w)
            xs.emplace_back(wsum, vsum);
    }
    for (int i = 0; i < 1 << res; i++)
    {
        i64 wsum = 0, vsum = 0;
        for (int j = 0; j < res; j++)
        {
            if (i >> j & 1)
            {
                wsum += ws[ofs + j];
                vsum += vs[ofs + j];
            }
        }
        if (wsum <= w)
            ys.emplace_back(wsum, vsum);
    }
    sort(xs.begin(), xs.end());
    sort(ys.begin(), ys.end());
    i64 ans = 0, maxi = 0;
    for (auto &p : xs)
    {
        i64 &x = p.second;
        x = max(x, maxi);
        maxi = max(x, maxi);
    }
    maxi = 0;
    for (auto &p : ys)
    {
        i64 &y = p.second;
        y = max(y, maxi);
        maxi = max(y, maxi);
    }
    for (auto &p : xs)
    {
        auto it = upper_bound(ys.begin(), ys.end(), make_pair(w - p.first + 1, (i64)0));
        it = prev(it);
        ans = max(ans, p.second + it->second);
    }
    cout << ans << endl;
}

int main()
{
    solve();
    return 0;
}

