with open("input.txt") as file:
    lines = [line.rstrip() for line in file]

first_digit = None
last_digit = None
things = []

for line in lines:
    first_digit = None
    last_digit = None
    for letter in line:
        if letter.isdigit():
            if first_digit is None:
                first_digit = letter
                last_digit = letter
            else:
                last_digit = letter
    things.append(int(f"{first_digit}{last_digit}"))

sum = 0
for thing in things:
    sum += thing

print(sum)