follows = """
Remove this line and paste the contents of following_accounts.csv here.
"""

import csv
from collections import Counter
from io import StringIO

follows = follows.strip()
follows_csv = iter(csv.reader(StringIO(follows)))
next(follows_csv)  # Ignore headers line

accounts = [line[0] for line in follows_csv]
instances = []
for username in accounts:
	instances.append(username.split("@")[1])
counts = Counter(instances)

print(f"{len(instances)} accounts followed in {len(counts)} instances.")
print(f"{sum(x[1] for x in counts.most_common() if x[1] == 1)} of the accounts followed are single ones from their instance.")
print("\nFollowed accounts per instance:")
print("\n".join(f"{x[0]}: {x[1]}" for x in counts.most_common()))