Keeping the rows in an array with specified numbers

I want to keep the part of the array with specified numbers in column 2. This deletes the rows in the array with the specified numbers in column 2, but how do I do the opposite (keep all rows where the numbers 5 or 6 are in column 2)?

numbersTokeep = [5,6];
A = magic(5);
for n = numbersToKeep
    A((A(:,2) == n),:) = [];
end

Answer 1

[Voss]

numbersTokeep = [5,6];
A = magic(5);
disp(A);

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

% keep rows where column 2 is 5 or 6:
A = A(ismember(A(:,2),numbersTokeep),:);
disp(A);

    23     5     7    14    16
     4     6    13    20    22

A = magic(5);
% or, delete rows where column 2 is not 5 or 6:
A(~ismember(A(:,2),numbersTokeep),:) = [];
disp(A);

    23     5     7    14    16
     4     6    13    20    22