A decimal integer literal contains any of the digits 0 through 9. The first digit cannot be 0.
.--------------. V | >>-digit_1_to_9----digit_0_to_9-+------------------------------><
Integer literals beginning with the digit 0 are interpreted as an octal integer literal rather than as a decimal integer literal.
The following are examples of decimal literals:
485976 -433132211 +20 5
A plus (+) or minus (-) symbol can precede the decimal integer literal. The operator is treated as a unary operator rather than as part of the literal.
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