int main()
{
    int n,a,b,c,s = 0,m = 0,t = 0;
    scanf("%d",&n);
    int i[50000],j[50000],k[50000];
    for(a = 0;;a++)
    {
       scanf("%d %d",&i[a],&j[a]);
       s++;
       if (i[a] == 0 && j[a] == 0)
         break;
    }
    for(a = 0;a < n;a++)
         k[a] = 0;
    for(a = 0;a < s-1;a++)
    {
          b = j[a];
          k[b]++;
    }
    for(a = 0;a < n;a++)
    {
          if(k[a] == (n-1))
          {
            c = k[a];
            b = a;
            for(a = 0;a < s-1;a++)
            {
               if(i[a] == b)
               m++;
            }
            if(m == 0)
            {     printf("%d\n",b);
                  t++;
            }
          }
    }
    if (t == 0)
      printf("NOT FOUND\n");
     }
