#include <fstream>

using namespace std;
const int N=10005;
int e[N], c[N], s[N];
int main()
{
    ifstream f("energii.in");
    ofstream g("energii.out");

    int G,W,i,j,k=0,minim;
    f>>G>>W;
    for(i=1;i<=G;i++)
        f>>e[i]>>c[i];

    for(i=1;i<=G;i++)
        for(j=W;j>=1;j--)
            if(j-e[i]>=0 && s[j-e[i]]+c[i]>s[j] && s[j]<W)
                    s[j]=s[j-e[i]]+c[i];

    minim=200000;
    for(i=1;i<=W;i++)
        if(s[i]>=W && s[i]<minim) {minim=s[i];k++;}

    if(k==0) g<<-1;
        else g<<minim;

    return 0;
}