#include <iostream>
#include<fstream>
using namespace std;
long e[1001][1001] , c[1001][1001] , energie[1001],cost[1001],ereq,n;
void read ()
{
    ifstream f("energii.in");
    f>>n>>ereq;
    for (int i=1;i<=n;i++)
        f>>energie[i]>>cost[i];

}
int memo[]={};
void compute ()
{
 long i,j;
 for (i=1;i<=n;i++)
  for (j=1;j<=n;j++)
     if (i==j)
      {
          e[i][j]=energie[i];
          c[i][j]=cost[i];
      }
     else
        {
        e[i][j]=energie[i]+energie[j];
        c[i][j]=cost[i]+cost[j];
        }
}
void search ()
{
    ofstream g("energii.out");
    long i,j; long mini=320000; int t=0;
    for (i=1;i<=n;i++)
         for (j=1;j<=n;j++)
          if (e[i][j]==ereq)
    {
        g<<c[i][j];
        return;
    }

        else if (e[i][j]>ereq)
        {
            t=1;
            if (c[i][j]>mini)
                mini=c[i][j];
        }
        if(t==1)
        g<<mini;
        else
            g<<-1;
}
int main()
{
    read();

    compute();
    search();

    return 0;
}