#include<iostream>
#include<fstream>

using namespace std;

ifstream f("energii.in");
ofstream g("energii.out");

int pret,t[100005],n,m,i,j,k,e,energ,energnec,minim;

int main()
{
f>>n>>energnec;

for(i=1;i<=100004;i++)t[i]=32000;
minim=32000;

for(i=1;i<=n;i++)
        {
        f>>energ>>pret;
        for(j=energnec;j>=0;j--)
                if(t[j+energ]>t[j]+pret)
                        {
                        t[j+energ]=t[j]+pret;
                        if(j+energ>=energnec)if(t[j+energ]<minim)minim=t[j+energ];
                        }
        if(t[energ]>pret)t[energ]=pret;
        }
if(minim==32000)g<<-1;
else g<<minim;
g.close();
return 0; 
}