int cyklicky(int x, int N)
{ if (x>N) return x-N; return x; }

void prejmenuj(vector<int> &A, int stare, int nove)
{
  for (int n=1; n < int(A.size()); n++)
    {
      if (stare < nove && A[n] > stare && A[n] <= nove)
	A[n]--;
      if (stare > nove && A[n] >= nove && A[n] < stare)
	A[n]++;
    }
}

void opacna_permutace(vector<int> &A)
{
  int N = A.size();
  int old = A[0];

  A[0] = cyklicky(A[0] + N/2, N);
  prejmenuj(A, old, A[0]);
  if (N % 2 == 0)
    return;

  int velke = (N+1)/2 + (A[0] <= N/2);
  if (A[1] >= velke)
    {
      old = A[0];
      A[0] = cyklicky(A[0] + 1, N);
      prejmenuj(A, old, A[0]);
    }

  prejmenuj(A, A[0], N);
  vector<int> B(A.begin()+1, A.end());
  opacna_permutace(B);
  for (int n=1; n<N; n++)
    A[n]=B[n-1];
  prejmenuj(A, N, A[0]);
}