The function for converting tricky-format digits

num2int.py

## Convert strings of 2-digits number have the following tricky format to an integer.
## Tricky format:　the last digit is described as decimal, and the first digit is chosen from {1, ..., 9, A, ..., Z, a, ..., z}.
## The min is 0(="00") and the max is 619(="z9").
## Example: "15" -> 15, "A0" -> 100, "Z9" -> 359, "a0" -> 360, "c5" -> 385

def num2int(num):
    if num.isdigit():
        return int(num)
    elif num[0].isupper():
        return int(num[0], 36) * 10 + int(num[1])
    else:
        return int(num[0], 36) * 10 + 260 + int(num[1])