#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=1444999994;
ll mod=1000000007;
int main(){
    ll n,m;
    cin >> n >> m;
    vector<pair<ll,ll>>p(n);
    for (ll i = 0; i < n; i++)
    {
        cin >> p[i].first >> p[i].second;
    }
    sort(p.begin(),p.end());
    reverse(p.begin(),p.end());
    vector<ll>v(n),w(n);
    for (ll i = 0; i < n; i++)
    {
        v[i]=p[i].first;
        w[i]=p[i].second;
    }
    vector<ll>dp(m+1,-1);
    dp[0]=0;
    ll ans=0;
    for (ll i = 0; i < n; i++)
    {
        for (ll j = m; j >=0; j--)
        {
            if (dp[j]==-1)
            {
                continue;
            }
            if (j+w[i]<=m)
            {
                if (dp[j+w[i]]<dp[j]+v[i])
                {
                    dp[j+w[i]]=dp[j]+v[i];
                    ans=max(ans,dp[j+w[i]]*v[i]);
                }
            }
        }
    }
    cout << ans << endl;
}