#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
int main()
{
    FILE *intrare;
    intrare=fopen("energii.in","r");

    if(intrare==NULL)
    {
        printf(intrare,"Fisierul nu s-a putut deschide");
        exit(1);
    }

    int G , W;
    int EG[10001] , CG[10001];
    fscanf(intrare, "%d %d", &G, &W);

    for(int i=0; i<G; i++)
    {
        fscanf(intrare, "%d %d",&EG[i],&CG[i]);
    }
    fclose(intrare);

    FILE *iesire;
    iesire=fopen("energii.out","w");

    if(iesire==NULL)
    {
        fprintf(iesire,"Fisierul nu s-a putut deschide");
        exit(1);
    }

    int CostMin=INT_MAX;
    for(int i=0; i<G; i++)
    {
        if(CG[i]<CostMin);
        {
            CostMin=CG[i];
        }
    }
    if(CostMin>=W)
    {
        fprintf(iesire,"%d",CostMin);
    }
    else
    {
        fprintf(iesire,"-1");
    }
    fclose(iesire);
}