#!/usr/bin/python

def find_high(dic):
    high, higha = -1, 'a'
    for a, b in dic.iteritems():
        if b > high:
            high, higha = b, a
    return higha

def freq_anal(phrase):
    lower_phrase = phrase.lower()
    freqs = dict([(a, 0) for a in 'abcdefghijklmnopqrstuvwxyz'])

    for a in phrase:
        if freqs.has_key(a):
            freqs[a] += 1
    
#   commonest = 'etaoinshrdlucmfwypvbgkqjxz'    # Linotype
#   commonest = 'eitsanhurdmwgvlfbkopjxczyq'    # Morse code
    commonest = 'etaoinshrdlcumwfgypbvkjxqz'    # Crypto

    etaoin = dict([(a, 0) for a in commonest])
    for a in commonest:
        etaoin[a] = find_high(freqs)
        del freqs[etaoin[a]]

    outstring = ''

    for a in phrase:
        if etaoin.has_key(a.lower()):
            if a.islower():
                outstring += etaoin[a]
            else:
                outstring += etaoin[a.lower()].upper()
        else:
            outstring += a
    
    return outstring