#include <fstream>
using namespace std;

ifstream cin ("energii.in");
ofstream cout ("energii.out");

int main ()
{
    int generatoare , energie_necesara;
    cin >> generatoare >> energie_necesara;

    int minim = -1 , energie , cost;
    for (int indice = 1 ; indice <= generatoare ; indice++)
    {
        cin >> energie >> cost;

        if (energie >= energie_necesara && (cost < minim || minim == -1))
            minim = cost;
    }

    cout << minim;
    cout.close(); cin.close();
    return 0;
}