#include <fstream>

using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int n,m,a,b,v[1000001]={-1},ok,p,ma,i,j;
int main()
{
    f>>n>>m;
    for (i=1;i<=n;i++)
    {
        f>>a>>b;

        for (j=m;j>=1;j--)
         if (v[j] && v[j+b]<a+v[j])
          v[j+b]=a+v[j];

          if (a>v[b])
           v[b]=a;
    }
    for (i=1;i<=1000000;i++)
     if (v[i]>=m)
     {
         g<<i;
         ok=1;
         break;
     }
     if (ok==0)g<<"-1";
    f.close();
    g.close();
}