DecodeSerNo.py

#!/usr/bin/env python3

AtoZ = ["A", "B", "C", "D", "E", "F", "G", "H",
        "I", "J", "K", "L", "M", "N", "O", "P",
        "Q", "R", "S", "T", "U", "V", "W", "X",
        "Y", "Z"]

MaxDictionary = {}

for i in AtoZ:
    MaxDictionary[i] = 0

#for i in AtoZ:
#    print (i, MaxDictionary[i])
#
#print ("---------")

SerialFile = open("SerNo.txt", "r")
for ALine in SerialFile:
    char = ALine[0]
    NumAsString = ALine[1:]
    NumAsInt = int(NumAsString)
    #print( char, NumAsString, NumAsInt, ALine)

    CurrentMax = MaxDictionary[char]
    if NumAsInt > CurrentMax:
        MaxDictionary[char] = NumAsInt
        #print ("Max for " + char + " now " + str(NumAsInt))

for i in AtoZ:
    print (i, MaxDictionary[i])