#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define mt make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define pb push_back
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;

const int R = 5001;

int N;
ll W, best;
vll v, w;

double relax(int i, ll sv, ll sw) {
    double ww = W - sw;
    double res = sv;
    for (int j = i; j < N; ++j) {
        double dw = min<double>(ww, w[j]);
        ww -= dw;
        res += dw / w[j] * v[j];
    }
    return res;
}

void f(int i, ll sv, ll sw) {
    if (i == N) {
        smax(best, sv);
        return;
    }

    double kanwa = relax(i, sv, sw);
    if (kanwa < best)return;

    if (sw + w[i] <= W) {
        f(i + 1, sv + v[i], sw + w[i]);
    }
    f(i + 1, sv, sw);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    vector<pll> vw;
    cin >> N >> W;
    rep(i, N) {
        ll x, y;
        cin >> x >> y;
        if (y <= W) {
            vw.emplace_back(x, y);
        }
    }

    N = sz(vw);
    sort(all(vw), [](pll x, pll y) { return x.first*1.0/x.second > y.first*1.0/y.second; });
    v = w = vll(N);
    rep(i, N)tie(v[i], w[i]) = vw[i];

    f(0, 0, 0);
    cout << best << endl;
}