#include <fstream>
using namespace std;
 ifstream f("energii.in");
 ofstream  cout("energii.out");
 #define inf 100000005
int i,j,n,w,p,e,Min,v[10001];
int main()
{
    f>>n>>e;
    for (i=1;i<=e;i++)
       v[i]=inf;
for (i=1;i<=n;i++)
{
    f>>w>>p;
for (j=e;j>=0;j--)
   if(v[j]!=inf)
       if(j+w>e){
            if(v[e]>v[j]+p)
                v[e]=v[j]+p;
          }
       else
        if(v[j+w]>v[j]+p)
             v[j+w]=v[j]+p;
}
if(v[e]!=inf)
   cout<<v[e];
 else
    cout<<-1;
return 0;
}