#! /usr/bin/python

# Usage:
# python3 python-ex-1.py infile outfile line_number

# Write to outfile the positive integers in the line[line_number] where both input and output files are in CSV format
# e.g. if inputfile ex-1-input.csv contains

# 5,Hello,45,,12
# 43,-7,World of Mine!,12
# Yo,3,200

# and the command-line calling sequence is:
# python3 python-ex-1.py ex-1-input.csv ex-1-output.csv 1

# Then the contents of ex-1-output.csv is the line, with no spaces:
# 43,12

import sys

def florp():
    f = open(sys.argv[1],'r')
    lines = f.read().split('\n')
    f.close()

    entries = lines[int(sys.argv[3])].split(',')
    out = [x for x in entries if x.isdigit() and int(x) > 0]
    f = open(sys.argv[2],'w')
    f.write(','.join(out))
    f.close()

florp()