#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    ifstream f("energii.in");
    ofstream s("energii.out");
    int w,g,eg[30],cg[30],i,aux,n=0;
    f>>g>>w;
    for(i=1;i<=g;i++)
        f>>eg[i]>>cg[i];
    for(i=1;i<g;i++)
        for(int j=i+1;j<=g;j++)
        if(cg[i]>cg[j])
        {
            aux=cg[i];
            cg[i]=cg[j];
            cg[j]=aux;
            aux=eg[i];
            eg[i]=eg[j];
            eg[j]=aux;
        }

    for(i=1;i<=g;i++){
        if(eg[i]>=w)
        {
            s<<cg[i];
            return 0;
            break;
        }
        else if(eg[i]<w)
            n++;
    }
    if(n)
        s<<-1;
}