frequencias = {
    'A': 14.63,
    'B': 1.04,
    'C': 3.88,
    'D': 4.99,
    'E': 12.57,
    'F': 1.02,
    'G': 1.30,
    'H': 1.28,
    'I': 6.18,
    'J': 0.40,
    'K': 0.02,
    'L': 2.78,
    'M': 4.74,
    'N': 5.05,
    'O': 10.73,
    'P': 2.52,
    'Q': 1.20,
    'R': 6.53,
    'S': 7.81,
    'T': 4.34,
    'U': 4.63,
    'V': 1.67,
    'W': 0.01,
    'X': 0.21,
    'Y': 0.01,
    'Z': 0.47
}

def afreq(string):
    # determinar a frequencia de cada caractere na string
    # comparar com a frequencia de cada caractere na lingua portuguesa
    # calcular a diferenca entre as frequencias

    str_freq = {}
    for c in string:
        if not c.isalnum():
            continue

        if c in str_freq:
            str_freq[c] += 1
        else:
            str_freq[c] = 1

    for c in str_freq:
        if not c.isalnum():
            continue

        str_freq[c] /= len(string)

    freq_sorted = dict(sorted(str_freq.items(), key=lambda item: item[1]))

    possiveis_chaves = []
    for c in frequencias:
        for k in freq_sorted:
            if abs(frequencias[c] - freq_sorted[k]) < 0.5:
                possiveis_chaves.append(ord(k) - ord(c))

    return possiveis_chaves