#include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto& (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define sar(a,n) cout<<#a<<":";rep(pachico,n)cout<<" "<<a[pachico];cout<<endl
#define svec(v) cout<<#v<<":";rep(pachico,v.size())cout<<" "<<v[pachico];cout<<endl
#define svecp(v) cout<<#v<<":";each(pachico,v)cout<<" {"<<pachico.first<<":"<<pachico.second<<"}";cout<<endl
#define sset(s) cout<<#s<<":";each(pachico,s)cout<<" "<<pachico;cout<<endl
#define smap(m) cout<<#m<<":";each(pachico,m)cout<<" {"<<pachico.first<<":"<<pachico.second<<"}";cout<<endl

using namespace std;

typedef pair<int,int> P;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<double> vd;
typedef vector<P> vp;
typedef vector<string> vs;

const int MAX_N = 100005;

ll n, W;

//価値, 重さ
void dfs(ll value, ll weight, ll& opt, int index, vl& vsum, vl& wsum, vector<pll>& vec)
{
    if(index == n){
        cmx(opt, value);
        return;
    }
    //使う
    if(weight + vec[index].se <= W){
        ll lm = W - weight + wsum[index];
        int id = upper_bound(all(wsum),lm) - wsum.begin();
        ll tvalue = value+vsum[id-1]-vsum[index];
        ll tweight = weight+wsum[id-1]-wsum[index];
        cmx(opt, tvalue);
        if(id == n+1){
            return;
        }
        if(tvalue+(__int128)vec[id-1].fi * (W - tweight) / vec[id-1].se > opt){
            dfs(value+vec[index].fi,weight+vec[index].se,opt,index+1,vsum,wsum,vec);
        }
    }
    //使わない
    ll lm = W - weight + wsum[index+1];
    int id = upper_bound(all(wsum),lm) - wsum.begin();
    ll tvalue = value+vsum[id-1]-vsum[index+1];
    ll tweight = weight+wsum[id-1]-wsum[index+1];
    cmx(opt, tvalue);
    if(id == n+1){
        return;
    }
    if(tvalue+(__int128)vec[id-1].fi * (W - tweight) / vec[id-1].se > opt){
        dfs(value,weight,opt,index+1,vsum,wsum,vec);
    }
}

ll solve(vector<pll>& vec)
{
    vl vsum(n+1, 0), wsum(n+1, 0);
    rep(i,n){
        vsum[i+1] = vsum[i] + vec[i].fi;
        wsum[i+1] = wsum[i] + vec[i].se;
    }
    ll opt = 0;
    dfs(0,0,opt,0,vsum,wsum,vec);
    return opt;
}

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    cin >> n >> W;
    vector<pll> vec(n);
    rep(i,n){
        cin >> vec[i].fi >> vec[i].se;
    }
    sort(all(vec),[&](pll& a,pll& b){
        return (__int128)a.fi * b.se > (__int128)a.se * b.fi;
    });
    cout << solve(vec) << "\n";
    return 0;
}