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,X,Y) for(long long (I)=(X);(I)<(Y);(I)++)
#define REP(I,X,Y) for(long long (I)=(Y)-1;(I)>=(X);(I)--)
#define ALL(X) (X).begin(),(X).end()
#define pb push_back
#define COUNT(V,X) upper_bound((V).begin(),(V).end(),X)-lower_bound((V).begin(),(V).end(),X)
#define debug(x) cerr<<#x<<':'<<x<<endl;
#define DEBUG(v) cerr<<#v<<':';for(auto x:v)cerr<<x<<' ';cerr<<endl;
#define INF 1000000007
#define LINF 1000000000000000007
#define EPS 1e-9
typedef long long ll;
 
signed main(){
  vector<pair<ll,ll>> vw1,vw2;
  vector<pair<ll,ll>> VW1,VW2;//2^20
  ll N,W;
  cin >> N >> W;
  ll v,w;
  if(N == 1){
    cin >> v >> w;
    if(w <= W){
      cout << v << endl;
    }
    else cout << 0 << endl;
    return 0;
  }
  FOR(i,0,N/2){
    cin >> v >> w;
    vw1.pb(make_pair(w,v));
  }
  FOR(i,0,(N+1)/2){
    cin >> v >> w;
    vw2.pb(make_pair(w,v));
  }
  VW1.pb(make_pair(0,0));
  VW2.pb(make_pair(0,0));
  FOR(i,0,vw1.size()){
    REP(j,0,VW1.size()){
      VW1.pb(make_pair(VW1[j].first+vw1[i].first,VW1[j].second+vw1[i].second));
    }
  }
  FOR(i,0,vw2.size()){
    REP(j,0,VW2.size()){
      VW2.pb(make_pair(VW2[j].first+vw2[i].first,VW2[j].second+vw2[i].second));
    }
  }
  sort(ALL(VW1));
  sort(ALL(VW2));
  map<ll,ll> m;
  vector<pair<ll,ll>> vvww;
  ll yay = -1;
  for(auto p:VW2){
    if(p.second > yay){
      vvww.pb(p);
      yay = p.second;
    }
  }
  ll ans = 0;
  for(auto p:VW1){
    if(p.first <= W){
      ans = max((*(upper_bound(ALL(vvww),make_pair(W-p.first,(ll)LINF))-1)).second+p.second,ans);
    }
  }
  cout << ans << endl;
}
