#include <iostream>
#include <vector>
#include <algorithm>
#include <atcoder/modint>
using namespace std;
using i64 = long long;
#define rep(i,n) for(int i=0; i<(int)(n); i++)
using modint = atcoder::static_modint<998244353>;


int N,M;
vector<pair<int,int>> VW;
vector<i64> dp;

int main(){
    cin >> N >> M;
    dp.assign(M+1, 0);
    VW.resize(N);
    rep(i,N){ int u,v; cin >> u >> v; VW[i] = {u,v}; }

    sort(VW.rbegin(), VW.rend());

    i64 ans = 0;
    for(auto [v,w] : VW){
        for(int to=M; to>=w; to--){
            dp[to] = max(dp[to], dp[to-w] + v);
        }
        for(auto a : dp) ans = max(ans, a * v);
    }

    cout << ans << endl;
    return 0;
}




struct ios_do_not_sync{
    ios_do_not_sync(){
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
    }
} ios_do_not_sync_instance;