#include <iostream>
#include <fstream>

using namespace std;

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

int main()
{
    int G,w,a[100],b[100],mini = 5002,gasit = 0;

    f >> G >> w;

    for(int i = 1;i <= G;i++)
    {
        f >> a[i];
        f >> b[i];
    }

    for(int i = 1;i <= G;i++)
    {
        if((a[i] >= w) && (b[i] < mini))
        {
            mini = b[i];
            gasit = 1;
        }
    }

    if(gasit == 0)
    {
        for(int i = 1;i <= G;i++)
        {
            for(int j = i + 1;i <= G;i++)
            {
                if(a[i] + a[j] >= w)
                {
                    if(b[i] + b[j] < mini)
                    {
                        mini = b[i] + b[j];
                    }
                }
            }
        }
    }
    g << mini;






    return 0;
}