#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ld = long double;

struct Product {
    ll v;
    ll w;
    bool operator<(const Product& p) const
    {
        return v * p.w < w * p.v;
    }
    bool operator>(const Product& p) const
    {
        return v * p.w > w * p.v;
    }
};
ostream& operator<<(ostream& os, const Product& p)
{
    os << "<" << p.v << ", " << p.w << ">";
    return os;
}

ll ans = 0;
int N;
ll W;

void dfs(const vector<Product>& product, const int ind, const ll weight, const ll value)
{
    if (ind == N) {
        ans = max(ans, value);
        return;
    }
    if (weight + product[ind].w <= W) {
        ld relaxed = value + product[ind].v;
        ll use = weight + product[ind].w;
        for (int i = ind + 1; i < N; i++) {
            if (use + product[i].w <= W) {
                use += product[i].w;
                relaxed += product[i].v;
            } else {
                relaxed += (ld)(product[i].v) / product[i].w * (W - use);
                use = W;
                break;
            }
        }
        if (relaxed > ans) {
            dfs(product, ind + 1, weight + product[ind].w, value + product[ind].v);
        }
    }
    ld relaxed = value;
    ll use = weight;
    for (int i = ind + 1; i < N; i++) {
        if (use + product[i].w <= W) {
            use += product[i].w;
            relaxed += product[i].v;
        } else {
            relaxed += (ld)(product[i].v) / product[i].w * (W - use);
            use = W;
            break;
        }
    }
    if (relaxed > ans) {
        dfs(product, ind + 1, weight, value);
    }
}

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

    cin >> N >> W;
    vector<Product> product;
    for (int i = 0; i < N; i++) {
        ll v, w;
        cin >> v >> w;
        if (w > W) {
            continue;
        }
        product.push_back(Product{v, w});
    }
    N = product.size();
    sort(product.begin(), product.end(), greater<Product>{});
    ll use = 0;
    for (int i = 0; i < N; i++) {
        if (use + product[i].w <= W) {
            ans += product[i].v;
            use += product[i].w;
        }
    }

    dfs(product, 0, 0, 0);
    cout << ans << endl;
    return 0;
}