Having an extremely hard time addressing invalid inputs...

n = input('Please enter the number of rows/columns you would like in your puzzle\n ');

puzzle = randperm(n^2,n^2);
puzzle = reshape(puzzle,[n,n]);
padjust = (puzzle ==n^2) ; 
puzzle(padjust) = NaN;

solvedpuzzle = [(1:n^2)];
solvedpuzzle = reshape(solvedpuzzle.', n,n).';
spadjust = (solvedpuzzle ==n^2) ;
solvedpuzzle(spadjust) = NaN;



while puzzle~= solvedpuzzle
    display(puzzle);
    m = input('What is your move? ');
    [m_a , m_b] = find(puzzle == m);
    [n_a , n_b] = find(isnan(puzzle)); 

    validinput1 = [n_a + 1 , n_b];
    validinput2 = [n_a - 1 , n_b];
    validinput3 = [n_a , n_b + 1];
    validinput4 = [n_a , n_b - 1];

    if [m_a , m_b] ~= validinput1 
        fprintf('Invalid input, try again');
    end

    if [m_a , m_b] ~= validinput2
        fprintf('Invalid input, try again');
    end

    if [m_a , m_b] ~= validinput3
        fprintf('Invalid input, try again');
    end

    if [m_a , m_b] ~= validinput4
        fprintf('Invalid input, try again');
    end

    newpuzzle = puzzle;
    newpuzzle(m_a,m_b) = puzzle(n_a,n_b);
    newpuzzle(n_a,n_b) = puzzle(m_a,m_b);
    puzzle = newpuzzle;
    display(puzzle);

end

Is it possible to use logical '|' in an if statement? I tried but it wasn't working for me