#include<bits/stdc++.h>
using namespace std;
#define sync ios_base::sync_with_stdio(false), cin.tie(NULL)
#define F first
#define S second
#define pb emplace_back
#define mt make_tuple
#define gcd __gcd
#define PI 3.141592653589
// Input
#define in(a) scanf("%d",&a)
#define in2(a,b) scanf("%d%d",&a,&b)
#define in3(a,b,c) scanf("%d%d%d",&a,&b,&c)
#define llin(a) cin >> a
#define inl(a) scanf("%lld",&a)
#define read(v,i,n) for(i=0;i<n;i++)in(v[i])
#define twod(mat,i,j,n,m) rep(i,n){rep(j,m)in(mat[i][j]);}
#define sc(ch) scanf("%c",&ch)
#define sstr(str) scanf("%s",str)
// Output
#define pr(a) printf("%d ",a)
#define pr2(a,b) printf("%d %d\n",a,b)
#define pr3(a,b,c) printf("%d %d %d\n",a,b,c)
#define out(a) printf("%d\n",a)
#define outl(a) printf("%lld\n",a)
#define llpr(a) cout << a << " "
#define llout(a) cout << a << "\n"
#define yes printf("YES\n")
#define no printf("NO\n")
#define lin printf("\n")
// Iterator
#define lp(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) for(i=0;i<n;i++)
#define all(vec) vec.begin(),vec.end()
#define lower(v,k) lower_bound(v.begin(),v.end(),k)-v.begin()
#define upper(v,k) upper_bound(v.begin(),v.end(),k)-v.begin()
#define tf(mytuple) get<0>(mytuple)
#define ts(mytuple) get<1>(mytuple)
#define tt(mytuple) get<2>(mytuple)
// Debug
#define dbg(v,i,n) for(i=0;i<n;i++)pr(v[i]); lin
#define what(x) cerr << #x << " : " << x << "\n"
#define ck printf("continue\n")
#define debug(args...) { string _s = #args; replace(_s.begin(), _s.end(), ',', ' '); stringstream _ss(_s); istream_iterator<string> _it(_ss); err(_it, args); }
void err(istream_iterator<string> it) {}
template<typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args)
{
	cerr << *it << " = " << a << "\n";
	err(++it, args...);
}
// Data Type
#define ll long long int
#define ii pair<int,int>
#define pli pair<ll,int>
#define triple tuple<int,int,int>
#define vi vector<int>
#define vii vector<pair<int,int> >
#define vvi vector<vector<int> >
#define viii vector<pair<pair<int,int>,int> >
#define vvii vector<vector<pair<int,int> > >
#define M 998244353
#define N 200005
ll pro(int x,int y)
{
    ll temp=x;
    temp*=y;
    return temp;
}
vector<vector<ll> > ad(4);
int main()
{
    int a,b,c,d,i,j,n,W,w;
    in2(n,W);
    w=0;
    rep(i,n)
    {
        in2(a,b);
        if(i==0)
            w=a;
        ad[a-w].pb(b);
    }
    rep(i,4)
        sort(all(ad[i])),reverse(all(ad[i]));
    rep(i,4)
    {
        lp(j,1,ad[i].size())
            ad[i][j]+=ad[i][j-1];
    }
    ll ans=0;
    ll total;
    rep(a,ad[0].size()+1)
    {
        rep(b,ad[1].size()+1)
        {
            rep(c,ad[2].size()+1)
            {
                rep(d,ad[3].size()+1)
                {
                    total=b+2*c+3*d;
                    total+=pro(a+b+c+d,w);
                    if(total<=W)
                    {
                        total=0;
                        if(a>0)
                            total+=ad[0][a-1];
                        if(b>0)
                            total+=ad[1][b-1];
                        if(c>0)
                            total+=ad[2][c-1];
                        if(d>0)
                            total+=ad[3][d-1];
                        ans=max(ans,total);
                    }
                }
            }
        }
    }
    llout(ans);
}







Measured memory_bytes: 256