#!/usr/bin/python3
"Compute a histogram of last-word frequencies for lines of input."
import sys, collections, math


def entropy(distribution):
    total = sum(v for k, v in distribution.items())
    p = dict((k, v/total) for k, v in distribution.items())
    return sum(v * -math.log(v)/math.log(2) for k, v in p.items())

if __name__ == '__main__':
    hist = collections.Counter(line.split()[-1] for line in sys.stdin)
    print(hist)
    print(entropy(hist), 'bits per item')