#include<fstream>;
using namespace std;
ifstream fin("energii.in");
ofstream fout("energii.out");
int main()
{
    long t[500000];
    long x,y,i,j,k,n,m,num,maxx,minn,maxxn,mp;


    fin>>n;"\n";
    fin>>m;"\n";
    fin>>x>>y;"\n";
    t[x]=y;
    minn=x;
    maxx=x;
    for (i=2;i<=n;i++)
    {
        fin>>x>>y;"\n";
        mp=minn;
        maxxn=maxx;
        for (j=minn;j<=maxx;j++)
        {
           if (t[j]>0)
           {
               if (t[j+x]==0) t[j+x]=t[j]+y; else
               if ((t[j+x]>0) && (t[j+x]>t[j]+y)) t[j+x]=t[j]+y;
               if (j+x>maxxn) maxxn=j+x;
           }
        }
        if (t[x]==0) t[x]=y; else
        if (t[x]>y) t[x]=y;
        if (x<mp) mp=x;
        minn=mp;
        maxx=maxxn;
    }
    mp=1000000;
    for (i=m;i<=maxx;i++)
    {
        if ((t[i]<mp) && (t[i]>=m)) mp=t[i];
    }
fout<<mp;

    return 0;
}