def main():
	real_input = ""
	tested = dict()

	with open('input.txt') as f:
		for line in f:
			real_input = line

	char_index = 0
	index = 0

	while len(tested) < 26:
		char = real_input[char_index].upper()

		if char in tested:
			char_index = char_index + 1
			continue

		index = 0
		input = real_input.replace(char, '')
		input = input.replace(char.lower(), '')

		while 1:
			if (index + 1) == len(input):
				break

			if (input[index] != input[index + 1]) and (input[index].upper() == input[index + 1].upper()):
				input = input[:index] + input[index + 2:]

				if index > 10:
					index = index - 10
				else:
					index = 0
				continue
			index = index + 1

		tested[char] = len(input)
		char_index = char_index + 1

	print(min(tested.values()))

main()
e11b73ba08897bc3fe68e5f85bf0cfcad060d090
<mask token>

def main():
    real_input = ''
    tested = dict()
    with open('input.txt') as f:
        for line in f:
            real_input = line
    char_index = 0
    index = 0
    while len(tested) < 26:
        char = real_input[char_index].upper()
        if char in tested:
            char_index = char_index + 1
            continue
        index = 0
        input = real_input.replace(char, '')
        input = input.replace(char.lower(), '')
        while 1:
            if index + 1 == len(input):
                break
            if input[index] != input[index + 1] and input[index].upper(
                ) == input[index + 1].upper():
                input = input[:index] + input[index + 2:]
                if index > 10:
                    index = index - 10
                else:
                    index = 0
                continue
            index = index + 1
        tested[char] = len(input)
        char_index = char_index + 1
    print(min(tested.values()))


<mask token>

def main():
    real_input = ''
    tested = dict()
    with open('input.txt') as f:
        for line in f:
            real_input = line
    char_index = 0
    index = 0
    while len(tested) < 26:
        char = real_input[char_index].upper()
        if char in tested:
            char_index = char_index + 1
            continue
        index = 0
        input = real_input.replace(char, '')
        input = input.replace(char.lower(), '')
        while 1:
            if index + 1 == len(input):
                break
            if input[index] != input[index + 1] and input[index].upper(
                ) == input[index + 1].upper():
                input = input[:index] + input[index + 2:]
                if index > 10:
                    index = index - 10
                else:
                    index = 0
                continue
            index = index + 1
        tested[char] = len(input)
        char_index = char_index + 1
    print(min(tested.values()))


main()

def main():
	real_input = ""
	tested = dict()

	with open('input.txt') as f:
		for line in f:
			real_input = line

	char_index = 0
	index = 0

	while len(tested) < 26:
		char = real_input[char_index].upper()

		if char in tested:
			char_index = char_index + 1
			continue

		index = 0
		input = real_input.replace(char, '')
		input = input.replace(char.lower(), '')

		while 1:
			if (index + 1) == len(input):
				break

			if (input[index] != input[index + 1]) and (input[index].upper() == input[index + 1].upper()):
				input = input[:index] + input[index + 2:]

				if index > 10:
					index = index - 10
				else:
					index = 0
				continue
			index = index + 1

		tested[char] = len(input)
		char_index = char_index + 1

	print(min(tested.values()))

main()