#include <fstream>
#include <algorithm>
#include <climits>
using namespace std;
ifstream in ("energii.in");
ofstream out ("energii.out");
struct info
{
    int energie;
    int valoare;
    double raport;
};
bool sortare (info a, info b)
{
    if (a.raport!=b.raport)
        return a.raport>b.raport;
    else
        return a.energie>b.energie;
}
info v[1001];
long long g,n,min1=INT_MAX;
int main()
{
    in>>n>>g;
    for (int i=1; i<=n; ++i)
    {
        in>>v[i].energie>>v[i].valoare;
        v[i].raport=1.0*v[i].energie/v[i].valoare;
    }
    sort(v+1,v+n+1,sortare);
    long long e=0,cnt=1,s=0;
    for (int i=1; i<=n; ++i)
    {
        cnt=i;
        while (e<g && cnt<=n)
        {
            s+=v[cnt].valoare;
            e+=v[cnt++].energie;
        }
        if (e>=g && s<min1)
            min1=s;
        e=0;
        s=0;
    }
    if (min1==INT_MAX)
        out<<-1;
    else
        out<<min1;
    return 0;
}