What is the total length of the first six chromosomes listed in the dataset?

What is the total length of the first six chromosomes listed in the dataset?: a task in data-agent-harbor-train (Harbor dataset). Files (in /home/user/input, no subfolders): - genome.fa - genes-augustus.csv - genes-genscan.csv - genes-ensembl.csv - genes-refseq.csv - genes-xeno-refseq.csv