Off topic:Calculate matrix of distances between sequences

Question

[moreirasarasousa]

Can someone help me with this question ?

For exercise 1 use pen and paper.

Consider the following multiple sequence alignment from a set of four sequences:

S1: A-CATATC-AT- S2: A-GATATT-AG- S3: AACAGATC-T-- S4: G-CAT--CGATT

1. Calculate the distance matrix. Assume the metric distance as the number of distinct characters in pairwise alignment (assume the pairwise alignment given by the multiple sequence alignment).

I really dont know how this is calculated manually