#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
typedef pair<double, bool> Pd;
int n; ll W;
ll v[5001], w[5001];
int ind[5001];
ll ans;

Pd rsolve(int i, double ws, double vs){
	bool ok=1;
	for(int k=i; k<n; k++){
		double x=min((double)W-ws, (double)w[ind[k]]);
		if(x>0 && x<(double)w[ind[k]]){
			ok=0;
		}
		ws+=x;
		vs+=x/(double)w[ind[k]]*(double)v[ind[k]];
	}
	return Pd(vs, ok);
}

ll solve(int i, ll ws, ll vs){
	if(i==n){
		ans=max(vs, ans);
		return vs;
	}
	Pd p=rsolve(i, (double)ws, (double)vs);
	if(p.second){
	    ans=max(ans, (ll)p.first);
	    return (ll)p.first;
	}
	if(p.first<(double)ans) return 0;
	ll ret=0;
	if(ws+w[ind[i]]<=W) ret=max(ret, solve(i+1, ws+w[ind[i]], vs+v[ind[i]]));
	ret=max(ret, solve(i+1, ws, vs));
	ans=max(ret, ans);
	return ret;
}

int main()
{
	cin>>n>>W;
	for(int i=0; i<n; i++){
		ind[i]=i;
		cin>>v[i]>>w[i];
	}
	sort(ind, ind+n, [&](int i, int j){ return (double)v[i]/(double)w[i]>(double)v[j]/(double)w[j];});
	solve(0, 0, 0);
	cout<<ans<<endl;
	return 0;
}