#include<stdio.h>
int main()
{
    int num[41],score[41],search,i,j,k,tem;
    for(i=1;;i++)
    {
         scanf("%d%d",&num[i],&score[i]);
         if((num[i]==-1)&&(score[i]==-1))
            break;

    }
    i--;
    for(j=1;j<i;j++)
    {
        for(k=j+1;k<=i;k++)
            if(num[j]>num[k])
            {
                    tem=num[k];
                num[k]=num[j];
                num[j]=tem;
                                tem=score[k];
                                score[k]=score[j];
                                score[j]=tem;
            }
    }
    scanf("%d",&search);
    for(j=0;j<=i;j++)
    if(search==num[i/2])
    {
         printf("%d",score[i/2]);
         break;
    }
    else if(search<num[i/2])
    {
        i=i/2;
    }
    else if(search>num[i/2])
    {
        i=i/2+i/4;
    }
        return 0;
}