#include<fstream>
using namespace std;
ifstream cin("rucsac.in");
ofstream cout("rucsac.out");
int s,g,n;
struct obiect
{
    int gr,val;
}v[5001];
void citire()
{

    cin>>n>>g;
    for(int i=1;i<=n;i++)
        cin>>v[i].gr>>v[i].val;
}
void ordonare()
{

    for(int i=1;i<=n-1;i++)
        for(int j=i+1;j<=n;j++)
        if(v[i].val/v[i].gr>v[j].val/v[i].gr)
    {
        v[0]=v[i];
        v[i]=v[j];
        v[j]=v[0];
    }
}
int solutie()
    {
        int ok=0;
        for(int i=n;i>=1&&ok==0;i--)
            if(g-v[i].gr>=0)
        {
            g=g-v[i].gr;
            s=s+v[i].val;
        }
        else ok=1;
        return s;

    }
int main()
{
    citire();
    ordonare();
    cout<<solutie();
    return 0;
}