#include <iostream>
#include <fstream>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int m[1010],e[1010],c[1010],i,j,w,n,sol;
int main()
{
f>>n>>w;
sol=999999999;
for (i=1;i<=n;i++)
{
    f>>e[i]>>c[i];
}
for (i=1;i<=n;i++)
{
    for (j=w;j>=1;j--)
    {
        if (m[j]!=0)
        {
            if (j+e[i]>=w)
            {
                if (sol==0) sol=m[j]+c[i];
                else sol=min(sol,m[j]+c[i]);
            }
        }
        if (m[e[i]]==0) m[e[i]]=c[i];
        else m[e[i]]=min(m[e[i]],c[i]);
        if (e[i]>=w) sol=min(sol,c[i]);
    }
}
if (sol==0) g<<sol-2;
else g<<sol;


    return 0;
}