#include <iostream>
#include <fstream>
using namespace  std;
ifstream f("energii.in");
ofstream gf("energii.out");

  int main()
{ short int g,w,i,c,e,s;
    float ef[1001],v[1001],u[1001],aux;
    f>>g;
    f>>w;
    for(i=1;i<=g;i++)
    {f>>v[i]>>u[i];}
    f.close();
     for(i=1;i<=g;i++)
     {  ef[i]=v[i]/u[i];}
       do
       {
         c=1;
       for(i=1;i<=g-1;i++)
       { if (ef[i]<ef[i+1])
           {aux=v[i];
        v[i]=v[i+1];
        v[i+1]=aux;
        aux=u[i];
        u[i]=u[i+1];
        u[i+1]=aux;
        aux=ef[i];
        ef[i]=ef[i+1];
        ef[i+1]=aux;
        c=0;
        } } }
    while (c==0);
         s=0;
         i=1;
         e=0;
     do
       { e=e+v[i];
         s=s+u[i];
         i++; }
     while((i<=g) && (e<w));
     cout<<s;
         return 0;
      }