Input File 
----------

First line: An integer showing the number (N) of entities you are
clustering.  Lines 2 to N+1: Labels for the entities.  These should be
strings, without spaces.  Following N*(N-1)/2 lines: The upper
diagonal matrix (free format).

For example, see file test.dis.

7
First
Second
Third
Fourth
Fifth
Sixth
Seventh
100.0 
100.0  
50.0  
33.0  
25.0  
20.0
100.0  
50.0  
50.0  
33.0  
33.0
100.0  
33.0  
20.0  
25.0
33.0  
20.0  
25.0
100.0 
100.0
100.0

By upper diagonal, I mean that the numbers are the similarities (or distances)
from comparison of entity 1 v 2, 1 v 3, 1 v 4, 1 v 5, 1 v 6, 1 v 7, 
                                 2 v 3, 2 v 4, 2 v 5, 2 v 6, 2 v 7,
                                        3 v 4, 3 v 5, 3 v 6, 3 v 7,
                                               4 v 5, 4 v 6, 4 v 7,
                                                      5 v 6, 5 v 7,
                                                             6 v 7.
In that order.