import os
for filename in os.listdir(os.getcwd()):
if filename.endswith(".txt"):
with open('{}' .format(filename), 'r+') as file:
lines = file.readlines()
file.seek(0, 0) #set the pointer to 0,0 cordinate of file
for line in lines:
row = line.strip().split(" ")
if not int(row[0]):
row[0] = '1'
print(row)
file.write(" ".join(row) + "
")