#include <iostream>
#include <fstream>
using namespace std;

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

int v[10000003];

int main()
{
    int n, maxim=0, minim, i, s1=0, s2=0, j, g, w, e, c;
    f>>g>>w;

    for (i=1;i<=g;i++)  {
        f>>e>>c;
        for (j=maxim;j>0;j--)
            if (v[j]!=0)
                if (v[j+e]==0)
                    v[j+e]=v[j]+c;
                else
                    if (v[j+e] > v[j]+c)
                        v[j+e]=v[j] + c;
            if (v[e]>c && v[e]!=0)
                v[e]=c;
            else
                v[e]=c;
                maxim=maxim+e;
    }
    minim = v[maxim];
    for (i=w;i<=maxim;i++)  {
        if (v[i] < minim && v[i]!=0)
            minim = v[i];

    }
    gout<<minim;
    f.close();
    gout.close();
    return 0;
}