we collect all the frequences and convert the frequencies in ordrer in to characters (ascii encoding) : ```pythondictio = {}with open("msg.txt") as fd :     data = fd.read() 
letters = []for i in data :     if i not in letters :         letters.append(i)    if i in dictio.keys() :         dictio[i] += 1    else :         dictio[i] = 1print("".join(list(map(lambda x : chr(dictio[x]) , letters))))```flag : `bcactf{ch4r4ct3r_fr3qu3ncy_15_50_c00l_55aFejnb}`