double sqr(double x)
{
  return x*x;
}

long foo(long ncities, double *x, double *y, double ThisX, double ThisY, double CloseDist, double *ThisDistp)
{
  long j=ncities;
  double ThisDist;
  do {
    j--;
    ThisDist = sqr(x[j]-ThisX)+sqr(y[j]-ThisY);
  } while (ThisDist > CloseDist);
  *ThisDistp = ThisDist;
  return j;
}