#Import the module that give us access to work with files. Allows us to manage the file-related input.
from io import open

# We open the txt document containing the calibration code
calibration_document=open('calibration_document.txt','r')

# We read the text inside distinguishing by lines
text=calibration_document.readlines()

# Close the txt file to be able to work on the text without having the file open.
calibration_document.close()
del(calibration_document)

# Define the digits that we want to search in the text
numbers = ['0','1','2','3','4','5','6','7','8','9']
calibration_value=0
list_numbers=[]

# Combining the first digit and the last digit to form a single two-digit number to obtein the calibration values
for line in text:
	code=''
	for letter in line:
		if letter in numbers:
			code=code+letter
			break
	for letter in line[::-1]:
		if letter in numbers:
			code=code+letter
			break
	list_numbers.append(int(code))

# The sum of all of the calibration values is the solution of the problem to to repare the trebuchet
calibration_values=sum(list_numbers)

#print(list_numbers)
print('The calibration value is {}'.format(calibration_values))