solution.py

# In a factory a printer prints labels for boxes.
# For one kind of boxes the printer has to use colors which, for the sake of simplicity,
# are named with letters from a to m.

# The colors used by the printer are recorded in a control string.
# For example a "good" control string would be aaabbbbhaijjjm meaning that the printer used three times color a,
# four times color b, one time color h then one time color a...

# Sometimes there are problems: lack of colors, technical malfunction and a "bad" control string is produced
# e.g. aaaxbbbbyyhwawiwjjjwwm with letters not from a to m.

# You have to write a function printer_error which given a string will output the error rate of the printer
# as a string representing a rational whose numerator is the number of errors and the denominator the length
# of the control string. Don't reduce this fraction to a simpler expression.

# The string has a length greater or equal to one and contains only letters from a to z.

# Examples:
# s="aaabbbbhaijjjm"
# error_printer(s) => "0/14"

# s="aaaxbbbbyyhwawiwjjjwwm"
# error_printer(s) => "8/22"


def printer_error(s):
    return f'{len([i for i in s if ord(i) > 109])}/{len(s)}'