def solution(matrix):
    m = len(matrix)
    n = len(matrix[0])

    for k in range((min(m, n) - 1) // 2 + 1):
        A = []

        for j in range(k, n - k):
            A.append(matrix[k][j])

        for i in range(k + 1, m - k):
            A.append(matrix[i][n - k - 1])

        for j in range(n - k - 2, k - 1, -1):
            A.append(matrix[m - k - 1][j])

        for i in range(m - k - 2, k, -1):
            A.append(matrix[i][k])

        A.sort()

        result_idx = 0

        for j in range(k, n - k):
            matrix[k][j] = A[result_idx]
            result_idx += 1

        for i in range(k + 1, m - k):
            matrix[i][n - k - 1] = A[result_idx]
            result_idx += 1

        for j in range(n - k - 2, k - 1, -1):
            matrix[m - k - 1][j] = A[result_idx]
            result_idx += 1

        for i in range(m - k - 2, k, -1):
            matrix[i][k] = A[result_idx]
            result_idx += 1

    return matrix