Error (4937): No visibility specified. Did you intend to add "public"?
 --> error_codes/input.sol:4:5:
  |
4 |     function f() {
  |     ^ (Relevant source part starts here and spans across multiple lines).

Warning (3420): Source file does not specify required compiler version!
--> error_codes/input.sol

Error (4247): Expression has to be an lvalue.
 --> error_codes/input.sol:5:9:
  |
5 |         2=0;
  |         ^

Error (7407): Type int_const 0 is not implicitly convertible to expected type int_const 2.
 --> error_codes/input.sol:5:11:
  |
5 |         2=0;
  |           ^

Error (2614): Indexed expression has to be a type, mapping or array (is literal_string "")
 --> error_codes/input.sol:6:9:
  |
6 |         ""[2];
  |         ^^