#include <iostream>
#include<fstream>
using namespace std;
fstream f("energii.in",ios::in);
fstream g("energii.out",ios::out);
int v[100],a[100],i,j,G,W,s,c;
float aux;
struct generator
{
    int x,y;
    float z;
};
generator gn[10];
int main()
{
    f>>G>>W;
    for(i=1;i<=G;i++)
      {
          f>>gn[i].x;f>>gn[i].y;
      }
      for(i=1;i<=G;i++)
        gn[i].z=(float)gn[i].x/gn[i].y;
        for(i=1;i<G;i++)
          for(j=i+1;j<=G;j++)
           if(gn[i].z<gn[j].z){aux=gn[i].x;
                                gn[i].x=gn[j].x;
                                 gn[j].x=aux;
                                 aux=gn[i].y;
                                gn[i].y=gn[j].y;
                                 gn[j].y=aux;
           }i=1;
           while(s<W)
           {
             s=s+gn[i].x;
              c=c+gn[i].y;
              i++;
           }
           g<<c;
           f.close();
           g.close();
    return 0;
}