Integer literal syntax

1 decimal_constant
1 octal_constant
1 hexadecimal_constant
2? 
2.0 l
2.0 L
2.0 ll
2.0 LL
2.1? 
2.1 u
2.1 U
2.0 u
2.0 U
2.1? 
2.1 l
2.1 L
2.1 ll
2.1 LL