#include <iostream>
#include <fstream>
using namespace std;

int main()
{
   ifstream f ("energii.in");
   ofstream k ("energii.out");
   struct eficient
    { float eg,cg;
    }v[1000];
    int g,w,i,s1=0,s2=0,j,c1=0,c2=0;
    float aux;
    f>>g>>w;
    for (i=1;i<=g;i++)
        f>>v[i].eg>>v[i].cg;
    for (i=1;i<g;i++)
     {for (j=i+1;j<=g;j++)
       {if (v[i].eg<v[i].eg)
       {
            aux=v[i];
           v[i]=v[j];
           v[j]=aux;


       }}}

   i=1; while (s2<w)
   {
       s2+=v[i].eg; c2+=v[i].cg;
        if ((v[i].eg==v[i+1].eg)&&(v[i].cg>v[i+1].cg))
          { s2-=v[i].eg; c2-=v[i].cg;}
   }



    for (i=1;i<g;i++)
     {for (j=i+1;j<=g;j++)
       {if (v[i].cg<v[i].cg)
       {
          aux=v[i];
           v[i]=v[j];
           v[j]=aux;

       }}}
   i=1; while (s1<w)
   {
       s1+=v[i].eg; c1+=v[i].cg;
       if ((v[i].eg==v[i+1].eg)&&(v[i].cg>v[i+1].cg))
          { s1-=v[i].eg; c1-=v[i].cg;}

   }

   if (c1>c2)k<<c2;
   else k<<c1;



    return 0;
}