#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <stdio.h>
using namespace std;
#define int long long
int MOD = 1000000007;
struct T {
	int v;
	int w;
	bool operator<(const T& right) const {
		return  v * right.w > right.v * w;
	}
};
struct State {
	int v;
	int w;
	//vector<int> goods;
	bool operator<(const State& right) const {
		return  v * right.w < right.v * w;
	}
};
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N, W;
	cin >> N >> W;
	vector<T> A(N);
	
	for (int i = 0; i < N; i++) {
		cin >> A[i].v >> A[i].w;
	}
	sort(A.begin(), A.end());
	int w = 0;
	int v = 0;
	priority_queue<State> pq;
	priority_queue<State> npq;
	State st;
	st.v = 0;
	st.w = 0;
	pq.push(st);
	int res = -1;
	for (int i = 0; i < N; i++) {
		while ((int)npq.size() > 0)npq.pop();
		for (int j = 0; j < 1000; j++) {
			if (pq.size() == 0) break;
			st = pq.top(); pq.pop();
			npq.push(st);
			st.v += A[i].v;
			st.w += A[i].w;
			if (st.w <= W) {
				res = max(res, st.v);
				npq.push(st);
			}
		}
		swap(pq, npq);
	}
	
	cout << res << endl;
}