MATLAB: I have a matrix A of size 523418*2, i want to delete repeating pair?? as i explained below. any help?

Question

a = [ 1 2 ; 2 1 ; 2 3 ; 5 2 ]

a =

1 2

2 1

2 3

5 2

i used following two logics,but neither gives my answer

>> uniqueresult = unique(sort(a,2), 'rows');

or

uniqueresult = unique(sort(a,2), 'rows','stable');

but this gives as following

uniqueresult =

1 2

2 3

2 5

but i want as

uniqueresult =

1 2

2 3

5 2

Answer 1

[~, tokeep] = unique(sort(a, 2), 'rows', 'stable');  %stable optional if you don't care about the ROW ordering
result = a(tokeep, :)