How can I remove redundant rows in matrix with respect two just first three columns?

A=       [1,1,4,5,6; 
          2,7,4,5,7;
          1,1,4,2,3;]

I want the matrix to remove redundant elements based on just first three columns, so my result should be

A = [1,1,4,5,6;
     2,7,4,5,7]

I tried

unique(A,'rows')

But it works for all the columns. How do I proceed with it?

Answer 1

[Walter Roberson]

[~, ia] = unique(A(:,1:3), 'rows', 'stable');
B = A(ia,:);