#include<fstream.h>
#include<math.h>
ifstream f("energii.in");
ofstream g("energii.out");
int gen,w,smin,i,j,emin,aux;
int a[1002],b[1002];
float c[1002];
int main ()
{
f>>gen>>w;
for(i=1;i<=gen;i++)
    {f>>a[i]>>b[i];
    c[i]=(float)a[i]/b[i];}
for(i=1;i<gen;i++)
    for(j=i+1;j<=gen;j++)
       if(c[i]<c[j])
	  {aux=a[i];
	  a[i]=a[j];
	  a[j]=aux;
	  aux=b[i];
	  b[i]=b[j];
	  b[j]=aux;
	  aux=c[i];
	  c[i]=c[j];
	  c[j]=aux;}
smin=0;
emin=0;
for(i=1;i<=gen;i++)
    {emin=emin+a[i];
    smin=smin+b[i];
    if(emin>=w)
      break;}
g<<smin<<"\n";
f.close();
g.close();
return 0;
}