#!/usr/bin/env python3

import string;
import random;

import os;
import sys;
 

if len(sys.argv) < 2:
    sys.exit('Usage: ' + os.path.basename(__file__) + ' length');

l = sys.argv[1];

if not l.isdigit():
    sys.exit('"' + l + '" is not a valid length.');

# cast l into intergers
l = int(l);

# define the character set
charSet = string.ascii_letters + string.digits;

# generate stack
out_stack = ''.join(random.choice(charSet) for x in range(l));

# Am I being piped?
if sys.stdout.isatty():
    print(out_stack);
else:
    sys.stdout.write(out_stack);