#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll n,m;
pair<ll,ll>a[500010];
ll dp[10010];
void solve1()
{
    for(int i=1;i<=n;i++)
        for(int j=m;j>=a[i].first;j--)
            dp[j]=max(dp[j],dp[j-a[i].first]+a[i].second);
    cout<<dp[m]<<'\n';
}
void solve2()
{
    ll num=m/a[1].first,res=0;
    for(int i=n;i>=max(n-num+1,1LL);i--) res+=a[i].second;
    cout<<res<<'\n';
}
void solve3()
{
    int pos,_pos;
    for(int i=1;i<=n;i++)
        if(a[i].first!=a[1].first)
        {
            _pos=pos=i-1;
            break;
        }
    ll now=0,val=0,res=0;
    while(pos&&now+a[pos].first<=m)
    {
        now+=a[pos].first;
        val+=a[pos].second;
        pos--;
    }
    res=val;
    for(int i=n;i>_pos;i--)
    {
        now+=a[i].first; val+=a[i].second;
        while(pos!=_pos&&now>m)
        {
            pos++;
            now-=a[pos].first;
            val-=a[pos].second;
        }
        if(now>m) break;
        res=max(res,val);
    }
    cout<<res<<'\n';
}
bool cmp(const pair<ll,ll>& s1,const pair<ll,ll>& s2)
{
    if(s1.second!=s2.second) return s1.second>s2.second;
    else return s1.first<s2.first;
}
int main()
{
    freopen("Mining.in","r",stdin);
    freopen("Mining.out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);
    cin>>n>>m;
    for(int i=1;i<=n;i++) cin>>a[i].second>>a[i].first;
    if(m<=1e4&&n<=1e3)
    {
        solve1();
        return 0;
    }
    sort(a+1,a+1+n);
    if(a[1].first==a[n].first)
    {
        solve2();
        return 0;
    }
    if(lower_bound(a+1,a+1+n,make_pair(a[1].first+1,0LL))->first==a[n].first)
    {
        solve3();
        return 0;
    }
    sort(a+1,a+1+n,cmp);
    ll res=0,now=0;
    for(int i=1;i<=n;i++)
    {
        if(a[i].first+now<=m)
        {
            now+=a[i].first;
            res+=a[i].second;
        }
    }
    cout<<res<<'\n';
    return 0;
}