class Solution:
    def movesToChessboard(self, board: List[List[int]]) -> int:
        W = len(board)
        H = len(board[0])

        rows = board
        cols = [[board[x][y] for x in range(W)] for y in range(H)]

        def _check_valid(lines: List[List[int]]) -> bool:
            c = Counter(line[0] for line in lines)
            if abs(c[0] - c[1]) > 1:
                return False

            for i in range(1, len(lines)):
                delta = 1 if lines[0][0] != lines[i][0] else 0
                for j in range(1, len(lines[0])):
                    if (delta + lines[0][j]) % 2 != lines[i][j]:
                        return False
            return True

        if not _check_valid(rows) or not _check_valid(cols):
            return -1

        def _min_swaps(lines: List[List[int]]) -> int:
            cnt = 0
            expected = 0
            for c in lines[0]:
                if c != expected:
                    cnt += 1
                expected = (expected + 1) % 2
            ans_cands = [cnt, len(lines[0]) - cnt]
            ans_cands = [ans for ans in ans_cands if ans % 2 == 0]
            assert ans_cands, "Should have at least one candidate"
            return min(ans_cands) // 2

        return _min_swaps(rows) + _min_swaps(cols)