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;

#define FOR(i, j, k) for(int i = j; i < k; ++i)
#define rep(i, j) FOR(i, 0, j)
#define FORr(i, j, k) for(int i = j; i >= k; --i)
#define repr(i, j) FOR(i, j, 0)
#define INF INT_MAX

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef pair<P, int> Pi;

const int MOD = 1000000007;
const int dy[] = { 0, 0, 1, -1 };
const int dx[] = { 1, -1, 0, 0 };

template <class T> void chmin(T& a, const T& b) { a = min(a, b); }
template <class T> void chmax(T& a, const T& b) { a = max(a, b); }

#define MAX_N 40

int n;
ll w[MAX_N], v[MAX_N];
ll W;

P ps[1 << (MAX_N/2)];

int main() {
	scanf("%d %lld", &n, &W);
	rep(i, n) scanf("%lld %lld", &v[i], &w[i]);
	int n2 = n / 2;
	rep(i, 1 << n2) {
		ll sw = 0, sv = 0;
		rep(j, n2) {
			if (i & (1 << j)) {
				sw += w[j];
				sv += v[j];
			}
		}
		ps[i] = P(sw, sv);
	}
	sort(ps, ps + (1 << n2));
	int m = 1;
	FOR(i, 1, 1 << n2) {
		if (ps[m - 1].second < ps[i].second) ps[m++] = ps[i];
	}
	ll res = 0;
	rep(i, 1 << (n - n2)) {
		ll sw = 0, sv = 0;
		rep(j, n - n2) {
			if ((i >> j) & 1) {
				sw += w[n2 + j];
				sv += v[n2 + j];
			}
		}
		if (sw <= W) {
			ll tv = (lower_bound(ps, ps + m, P(W - sw, LLONG_MAX)) - 1)->second;
			res = max(res, sv + tv);
		}
	}
	printf("%lld\n", res);
	return 0;
}