#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;

struct Item {
    bool operator<(const Item& o) const {
        return (double)v * o.w < (double)o.v * w;
    }
    Item& operator+=(const Item& o) {
        v += o.v;
        w += o.w;
        return *this;
    }
    int64_t v, w;
};

vector<Item> o, s;
int64_t v_max;

template <class F>
int lower_bound(int i0, int i1, F f) {
    while (i0 < i1) {
        int i = (i0 + i1) / 2;
        if (f(i)) i1 = i; else i0 = i + 1;
    }
    return i0;
}

void dfs(int d, int64_t v, int64_t w) {
    if (d == 0 || w == 0) {
        v_max = max(v_max, v);
        return;
    }

    int d1 = lower_bound(0, d, [&](int d1) {
        return s[d].w - s[d1].w <= w;
    });
    int64_t v1 = v + (s[d].v - s[d1].v), w1 = w - (s[d].w - s[d1].w);

    if (d1 == 0 || w1 == 0) {
        v_max = max(v_max, v1);
        return;
    }

    if (v_max - v1 >= (double)o[d1 - 1].v / o[d1 - 1].w * w1) return;

    d--;
    int64_t w2 = w - o[d].w;
    if (w2 >= 0) dfs(d, v + o[d].v, w2);
    dfs(d, v, w);
}

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

    int n;
    cin >> n;

    int64_t W;
    cin >> W;

    o.resize(n);
    for (int i = 0; i < n; i++) {
        cin >> o[i].v >> o[i].w;
    }

    sort(o.begin(), o.end());
    s.resize(n + 1);
    Item t = { 0, 0 };
    s[0] = { 0, 0 };
    for (int i = 0; i < n; i++) {
        t += o[i];
        s[i + 1] = t;
    }

    v_max = 0;
    dfs(n, 0, W);

    cout << v_max << endl;

    return 0;
}