if __name__ == "__main__":

    # Problem I
    x = int(input("Enter a number from 1 to 20: "))
    x = ((x * 2 + 10) / 2) - x
    print(x)

    # Problem II
    a = int(input("Enter first number: "))
    b = int(input("Enter second number: "))
    c = a + b
    d = b + c
    e = c + d
    f = d + e
    g = e + f
    h = f + g
    i = g + h
    j = h + i
    print((a + b + c + d + e + f + g + h + i + j) / g)

    # Problem III
    num = int(input("Enter a 4-digit number: "))
    a = num // 1000
    a1 = a * 1000
    b = num % 10
    b2 = b * 1000
    num2 = (num - a1 + b2 - b + a)
    smaller = min(num, num2)
    larger = max(num, num2)
    subtract = larger - smaller
    digit_thousand = subtract // 1000
    digit_hundred = subtract % 1000 // 100
    digit_one = subtract % 10
    digit_ten = subtract % 100 // 10
    digit_added = digit_thousand + digit_hundred + digit_one + digit_ten
    two_digit_add = (digit_added % 10) + (digit_added // 10)
    print(two_digit_add)

    # Problem IV
    num = int(input("Enter a number not divisible by 7: "))
    divided = num / 7
    num1 = (divided * 1000000)
    digit1 = (num1 % 1000000 // 100000)
    digit2 = (num1 % 100000 // 10000)
    digit3 = (num1 % 10000 // 1000)
    digit4 = (num1 % 1000 // 100)
    digit5 = (num1 % 100 // 10)
    digit6 = (num1 % 10)
    print(int(digit1 + digit2 + digit3 + digit4 + digit5 + digit6))