#include <fstream>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int n,co,x,y,s,i,j,mi,b[10000001];
int main()
{   f>>n>>co;
    f>>x>>y;
    b[x]=y;
    s=x;
    for (i=2;i<=n;++i) {
        f>>x>>y;
        for (j=s;j>=1;--j) {
            if (b[j]>0)
                if (b[j+x]==0 || b[j+x]<b[j]+y)
                    b[j+x]=b[j]+y;}
        if (b[x]==0 || b[x]>y)
            b[x]=y;
        s+=x;}
    mi=999999999;
    for (i=co;i<=s;++i)
        if (b[i]<mi && b[i]>0)
            mi=b[i];
    if (mi==999999999)
        g<<-1<<'\n';
    else
        g<<mi<<'\n';

    return 0;
}