#include <iostream>
#include <fstream>
#include <climits>

using namespace std;
ifstream fin("energii.in");
ofstream fout("energii.out");



int n,E,d[15005],j,sol=INT_MAX,i;
struct centrala{
int e,c;}v[1005];
int main()
{
    fin>>n>>E;
    for (i=1; i<=n; i++)
    fin>>v[i].e>>v[i].c;


    for (i=0; i<=15000; i++)
        d[i]=INT_MAX;

    for (i=1; i<=n; i++)
    {
        for (j=E; j>=0; j--)
        {
            if (d[j]!=INT_MAX)
                d[j+v[i].e]=min(d[j+v[i].e],d[j]+v[i].c);
        }

        d[v[i].e]=min(d[v[i].e],v[i].c);
    }


    for (i=E; i<=15000; i++)
        sol=min(sol,d[i]);

    if (sol==INT_MAX)
        fout<<-1;
    else
        fout<<sol;



    return 0;
}