The printed form of an integer consists of a sequence of digits
optionally preceded by a minus sign (`-`

). These are normally
interpreted as base 10 integers. It is also possible to enter
integers in other bases (1 through 36); this is done by preceding the
digit string by the base (in decimal) followed by an apostrophe. If a
base greater than 10 is used, the characters A-Z or a-z are used to
stand for digits greater than 9.

Examples of valid integer representations are:

1 -2345 85923 8'777 16'3F4A -12'2A9

Note that

+525

is not a valid integer.

A base of zero will return the ASCII code of the (single) character after the quote; for example,

0'a = 97