[Python] Maps played reader

index =  0
words = ""
realmaps = []
final = 0

def isNum(s):
    try:
        int(s)
        return True
    except ValueError:
        return False

for line in open("bzfile.txt"):
    words += line


for word in words.split():
    if(word == 'Maps'):
        realmaps.append(prevword)
    prevword = word

for num in realmaps:
    print(num)
    if(isNum(num)):
        final += int(num)


print("Maps played: " + str(final))