#include <bits/stdc++.h>

using namespace std;

//ifstream f("file.in");

ifstream f("rucsac.in");
ofstream g("rucsac.out");

int n, G;
vector<pair<int, int> > v;

int main()
{


    f>>n>>G;
    //cout<<n<<G;
    for(int i=0; i<n; i++)
    {
        int a, b;
        f>>a>>b;
        //cout<<a<<" "<<b<<endl;
        v.push_back(make_pair(b, a));
    }

    sort(v.begin(), v.end());

    int greutate, rez;

    if(v[n-1].second <= G) {
        greutate = v[n-1].second;
        rez = v[n-1].first;
    }

    for(int i=n-2; i>=0; i--)
    {
        if(greutate + v[i].second <= G) {
            greutate += v[i].second;
            rez += v[i].first;
        }
    }

    g<<rez;

    return 0;
}