#include #include #include using namespace std; int N; deque A, B; bool is_metalike_now() { for (int i = 0; i < N; i++) { if (i+1 < (N+1)/2 && !(A[i] < B[i])) { return false; } if (i+1 > (N+1)/2 && !(A[i] > B[i])) { return false; } if (A[i] != B[N - i - 1]) { return false; } } return true; } // Simulate 2*N seconds. // Given a vector M of O(1) candidate midpoints (index of the middle elem if N // is odd, or right after the middle if N even), return the first time that: // - some m in M becomes the midpoint floor(N/2) (both even and odd N), and // - is_meta_like() holds true. int check(vector M) { for (int t = 0; t <= 2*N; t++) { for (int m : M) { if (m == N/2 && is_metalike_now()) { return t; } } A.push_back(B[0]); B.push_back(A[0]); A.pop_front(); B.pop_front(); for (int i = 0; i < (int)M.size(); i++) { if (--M[i] < 0) { M[i] += N; } } } return -1; } int solve() { cin >> N; A.resize(N); B.resize(N); for (int i = 0; i < N; i++) { cin >> A[i]; } for (int i = 0; i < N; i++) { cin >> B[i]; } // Handle any equal pairs. vector eq; for (int i = 0; i < N; i++) { if (A[i] == B[i]) { if (N % 2 == 0) { return -1; } eq.push_back(i); } } if (eq.size() > 1) { return -1; } if (eq.size() == 1) { return check({eq[0]}); } // From here on, guaranteed that A[i] != B[i]. // Check the number of times that A[i] < B[i] flips. vector flipped; for (int i = 1; i < N; i++) { if ((A[i - 1] < B[i - 1]) != (A[i] < B[i])) { flipped.push_back(i); } } if (flipped.size() > 1) { return -1; } // Might as well consider elements 0 and N-1 to be midpoints. flipped.push_back(0); flipped.push_back(N-1); return check(flipped); } int main() { int T; cin >> T; for (int t = 1; t <= T; t++) { cout << "Case #" << t << ": " << solve() << endl; } return 0; }