#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
ll n,W;
ll nowbest=0;
vpl v;
void dfs(ll depth,ll value,ll weight){
    if(depth==n){
        return;
    }
    if(W-weight>=v[depth].second){
        value+=v[depth].first;chmax(nowbest,value);
        weight+=v[depth].second;
        double ld=0;
        ll ret=W-weight;
        for(ll k=depth+1;k<n;k++){
            if(ret>=v[k].second){
                ret-=v[k].second;
                ld+=v[k].first;
            }
            else{
                ld+=double(v[k].first)*ret/v[k].second;
                break;
            }
        }
        if(ld+value>=double(nowbest)){
            dfs(depth+1,value,weight);
        }
        value-=v[depth].first;
        weight-=v[depth].second;
    }
    double ld=0;
    ll ret=W-weight;
    for(ll k=depth+1;k<n;k++){
        if(ret>=v[k].second){
            ret-=v[k].second;
            ld+=v[k].first;
        }
        else{
            ld+=double(v[k].first)*ret/v[k].second;
            break;
        }
    }
    if(ld+value>=double(nowbest)){
        dfs(depth+1,value,weight);
    }
}
int main(){
    cin >> n >> W;
    v.resize(n);
    rep(i,n){
        ll a,b;cin >> a >> b;
        v[i]=make_pair(a,b);
    }
    sort(all(v),[](pl a,pl b){return double(a.first)/a.second>double(b.first)/b.second;});
    dfs(0,0,0);
    cout << nowbest << endl;
}