#include <fstream>

using namespace std;

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

void citire();
void sortare();
void rezolvare();

int n,p,i,v[100],c[100],nr,sortat=0,t,j,q,s;

int main()
{

    f>>n>>q;
    for(i=1;i<=n;i++)
        f>>v[i]>>c[i];

    for(i=1;i<=n;i++)
        for(j=i;j<=n;j++)
            if(c[j]>c[i])
    {
        t=c[i],p=v[i];
        c[i]=c[j],v[i]=v[j];
        c[j]=t,v[j]=p;
    }

    i=1;
    while(nr<q)
        {
            s+=c[i];
            nr+=v[i];
            i++;


        }
    g<<s;

    return 0;
}