Python program outputting numbers followed by 'L'

Question

I created a program in Python to generate any number of elements in the sequence of fibonacci or lucas numbers (fibonacci being 1,1,2,3,5,8,13 etc and lucas being 2,1,3,4,7,11,18 etc) but for some reason whenever I ran it for particular numbers (seemingly above a certain threshold), it outputted the number followed by a capital L. The first number it did this for was 2971215073, but other programs generate numbers far higher than that with no problem. How do I stop it from doing so? The code in its entirety:

import time
f = [1,1]
l = [2,1]
x = True
while x == True:
    b = raw_input('Would you like to generate fibonacci numbers (enter f) or lucas numbers (enter l)?\n')
    if b == 'l' or b == 'L' or b == 'lucas' or b == 'Lucas':
        z = True
        x = False
    elif b == 'f' or b == 'F' or b == 'fibonnaci' or b == 'Fibonnaci' or b == 'Fibonacci' or b == 'fibonacci':
        z = False
        x = False
    else:
        print 'That isn\'t an answer. Enter f or l.'
y = True
while y == True:
    c = raw_input('Would you like to generate up to a limit (enter a) or a certain number of elements (enter b)?\n')
    if c == 'A' or c == 'a':
        w = True
        y = False
    elif c == 'B' or 'b':
        w = False
        y = False
    else:
        print 'That isn\'t an answer. Enter a or b.'
a = input('Enter an upper bound.\n')
c = 1
if z == True and w == True:
    start = time.clock()
    while((l[c] + l[c-1]) <= a):
        l += [(l[c] + l[c-1])]
        c += 1
    print l
    if (time.clock() - start) >= 60:
        print 'Program took ' + str(time.clock() - start) + ' seconds to run.'
if z == True and w == False:
    start = time.clock()
    while(c-1 <= a-3):
        l += [(l[c] + l[c-1])]
        c += 1
    print l
    if (time.clock() - start) >= 60:
        print 'Program took ' + str(time.clock() - start) + ' seconds to run.'
if z == False and w == True:
    start = time.clock()
    while((f[c] + f[c-1]) <= a):
        f += [(f[c] + f[c-1])]
        c += 1
    print f
    if (time.clock() - start) >= 60:
        print 'Program took ' + str(time.clock() - start) + ' seconds to run.'
if z == False and w == False:
    start = time.clock()
    while(c-1 <= a-3):
        f += [(f[c] + f[c-1])]
        c += 1
    print f
    if (time.clock() - start) >= 60:
        print 'Program took ' + str(time.clock() - start) + ' seoonds to run.'
raw_input('Press enter to exit.')

An example of the output:

Would you like to generate fibonacci numbers (enter f) or lucas numbers (enter l)?
f
Would you like to generate up to a limit (enter a) or a certain number of elements (enter b)?
b
Enter an upper bound.
100



  [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597,
 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811,
     514229, 832040, 1346269, 2178309, 3524578, 5702887, 9227465, 14930352,
     24157817, 39088169, 63245986, 102334155, 165580141, 267914296, 433494437, 701408733, 1134903170, 1836311903, 2971215073L, 4807526976L, 7778742049L,
     12586269025L, 20365011074L, 32951280099L, 53316291173L, 86267571272L,
     139583862445L, 225851433717L, 365435296162L, 591286729879L, 956722026041L, 1548008755920L, 2504730781961L, 4052739537881L, 6557470319842L, 
    10610209857723L, 17167680177565L, 27777890035288L, 44945570212853L, 
    72723460248141L, 117669030460994L, 190392490709135L, 308061521170129L, 
    498454011879264L, 806515533049393L, 1304969544928657L, 2111485077978050L,
     3416454622906707L, 5527939700884757L, 8944394323791464L, 14472334024676221L,
     23416728348467685L, 37889062373143906L, 61305790721611591L, 
    99194853094755497L, 160500643816367088L, 259695496911122585L, 420196140727489673L, 679891637638612258L, 1100087778366101931L, 1779979416004714189L, 2880067194370816120L, 4660046610375530309L,
     7540113804746346429L, 12200160415121876738L, 19740274219868223167L,
     31940434634990099905L, 51680708854858323072L, 83621143489848422977L,
     135301852344706746049L, 218922995834555169026L, 354224848179261915075L]
        Press enter to exit.

Answer 1

The L is a quirk of Python 2 that indicates "long integers". If you print the numbers individually (rather than printing the list), there would be no "L". Another option would be to upgrade to Python 3, which did away with this quirk.

Consider replacing:

print l

with

print ", ".join(str(x) for x in l)

If you still want the square brackets, then you can use formatting:

print "[{}]".format(", ".join(str(x) for x in l))