#include <fstream>
#define INF 6000000005
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
struct Rucsac{
int Profit;
int Weight;
};
Rucsac Arr[1002];
long long DP1[10002],DP2[10002];
int N,G;
void Read()
{
    int i;
    f>>N>>G;
    for(i=1;i<=5002;i++)
        DP1[i]=DP2[i]=INF;
    for(i=1;i<=N;i++)
        f>>Arr[i].Weight>>Arr[i].Profit;
}
void Solve()
{
    int i=1,j,last;
    for(i=1;i<=Arr[1].Weight;i++)
    {
            DP1[i]=Arr[1].Profit;
    }
    last=Arr[1].Weight;
    for(i=2;i<=N;i++)
    {
        DP1[Arr[i].Weight]=Arr[i].Profit;
        for(j=1;j<=last+Arr[i].Weight && j<=G;j++)
        {
            if(j>=Arr[i].Weight)
            {
               DP2[j]=min(DP1[j],DP1[j-Arr[i].Weight]+Arr[i].Profit);
               continue;
            }
           DP2[j]=DP1[j];
        }
        DP2[Arr[i].Weight]=Arr[i].Profit;
        for(j=max(min(last+Arr[i].Weight,G),Arr[i].Weight)-1;j>=1;j--)
            DP2[j]=min(DP2[j+1],DP2[j]);
        for(int k=1;k<=last+Arr[i].Weight && k<=G;k++)
            DP1[k]=DP2[k];
        last=last+Arr[i].Weight;
    }
    if(DP2[G]!=INF)
        g<<DP2[G]<<"\n";
    else
        g<<-1<<"\n";
}
int main()
{
    Read();
    Solve();
    return 0;
}