Check for repeated values in two cell arrays in matlab

I have 2 cells with 5 columns and I want to verify whether there are no repetitions in the values of the 1st columns. For example:

a={ 701  452  8  407  31
1037  110  14  873  93
*7985*   881  20  16  69
9420  481  9  191  95}

b={4220  308  118  464  24
*7985*   112  58  37  19
9639  61  29  96  21
9999    34      16      89      37}

In the 3rd row of a & in the 2nd row of b the values of the first column are equal . In that case I would like to obtain a new variable that identifies the lines in which the values are the same.

ab={3 2}

Can someone help me? Thanks

Answer 1

[Azzi Abdelmalek]

a={ 701  452  8  407  31
1037  110  14  873  93
7985   881  20  16  69
9420  481  9  191  95}
b={4220  308  118  464  24
7985   112  58  37  19
9639  61  29  96  21
9999    34      16      89      37}
a1=[a{:,1}]
b1=[b{:,1}]
[ii,ii]=find(ismember(a1,b1))
[jj,jj]=find(ismember(b1,a1))
out={ii' jj'}