#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
typedef long long ll;
typedef pair<int, int> P;

template <typename T, typename U>
auto Sum(T a, U b) -> decltype(a + b)
{
    return a + b;
}

template <typename T, typename U>
inline bool amax(T &a, U b)
{
    if (b > a)
    {
        a = b;
        return true;
    }
    return false;
}
template <typename T, typename U>
inline bool amin(T &a, U b)
{
    if (b < a)
    {
        a = b;
        return true;
    }
    return false;
}

int main()
{
    int N, M;
    cin >> N >> M;
    vector<P> items(N);
    rep(i, N) cin >> items[i].first >> items[i].second;
    sort(items.begin(), items.end(), [](P x, P y)
         { return x.first > y.first; });
    ll ans = 0;
    vector<ll> dp(M + 1);
    for (auto &p : items)
    {
        int v = p.first, w = p.second;
        for (int j = M; j >= w; --j)
        {
            amax(dp[j], dp[j - w] + v);
        }
        amax(ans, dp[M] * v);
    }
    cout << ans << endl;
}