#include <bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back
#define pcnt __builtin_popcount
#define show(x) cout<<#x<<" = "<<x<<endl;
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define fi first
#define se second
#define rng(a) a.begin(),a.end()
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define sz(x) (int)(x).size()
#define mp make_pair

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef set<int> si;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pll> vpll;
typedef set<ll> sl;
typedef __int128_t lll;
typedef pair<lll,lll> plll;
typedef vector<plll> vplll;
template<typename T>string join(vector<T>&v){stringstream s;FOR(i,0,sz(v))s<<' '<<v[i];return s.str().substr(1);}
ll gcd(ll a,ll b){if(a>b)swap(a,b);for(;a>0;b%=a,swap(a,b));return b;}
int modpow(ll a,ll n,int m){if(a==0)return a;ll p=1;for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;return(int)p;}
void dout(double d){printf("%.12f\n",d);}

const int iinf = 1e9;
const ll linf = 1e18;
const int mod = 1e9+7;
const double pi = acos(-1);
const double eps = 1e-10;
lll n, w, ans;
vplll x;
int md;
void searc(int d, lll sv, lll sw){
  if(d >= md){
    maxs(ans, sv);
    return;
  }
  int _d = d;
  lll _sv = sv, _sw = sw;
  while(_d < md && _sw + x[_d].se <= w){
    _sv += x[_d].fi;
    _sw += x[_d].se;
    _d++;
  }
  maxs(ans, sv);
  if(_d == md) return;
  if((ans-_sv)*x[_d].se >= (w-_sw)*x[_d].fi) return;
  if(w-sw >= x[d].se) searc(d+1, sv+x[d].fi, sw+x[d].se);
  searc(d+1, sv, sw);
}
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll _n, _w, _v;
  cin >> _n >> _w;
  n = _n;
  w = _w;
  FOR(i, 0, n){
    cin >> _v >> _w;
    if(_w > w) continue;
    x.pb(mp(_v, _w));
  }
  sort(rng(x), [](plll&a, plll&b){return a.fi*b.se > b.fi*a.se;});
  md=sz(x);
  searc(0, 0, 0);
  cout << ll(ans) << endl;
  return 0;
}