#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  vector<pair<int, int>> v(n);
  rep(i, n) cin >> v[i].first >> v[i].second;
  sort(v.rbegin(), v.rend());
  ll ans = 0;
  constexpr ll INF = 1e11;
  vector dp(n + 1, vector<ll>(m + 1, -INF));
  dp[0][0] = 0;
  rep(i, n) {
    rep(j, m + 1) {
      dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
      if (j + v[i].second <= m) {
        dp[i + 1][j + v[i].second] = max(dp[i + 1][j + v[i].second], dp[i][j] + v[i].first);
        ans = max(ans, v[i].first * dp[i + 1][j + v[i].second]);
      }
    }
  }
  cout << ans << '\n';
  return 0;
}