Language: C++

import java.util.Scanner;
import static java.lang.System.out;
class Main{
  public static void main(String args[]){
    Scanner scan = new Scanner(System.in);
    String name[] = {"black","blue","lime","aqua","red","fuchsia","yellow","white"};
    int color[][] = {{0,0,0},{0,0,255},{0,255,0},{0,255,255},{255,0,0},{255,0,255},{255,255,0},{255,255,255}};
    while(true){
      String str = scan.next();
      if(str.equals("0")) break;

      int R = Integer.parseInt(str.substring(1,3),16);
      int G = Integer.parseInt(str.substring(3,5),16);
      int B = Integer.parseInt(str.substring(5,7),16);
      double min = Double.MAX_VALUE;
      int Index = 0;
      for(int i = 0 ; i < 8 ; i++){
        double near = Math.sqrt(Math.pow(R - color[i][0],2) + Math.pow(G - color[i][1],2) + Math.pow(B - color[i][2],2));
        if( near < min ){
          min = near;
          Index = i;
        }
      }
      out.println(name[Index]);
    }
  }
}

Compiler output:
a.cc:1:1: error: 'import' does not name a type
    1 | import java.util.Scanner;
      | ^~~~~~
a.cc:1:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:2:1: error: 'import' does not name a type
    2 | import static java.lang.System.out;
      | ^~~~~~
a.cc:2:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:4:9: error: expected ':' before 'static'
    4 |   public static void main(String args[]){
      |         ^~~~~~~
      |         :
a.cc:4:27: error: 'String' has not been declared
    4 |   public static void main(String args[]){
      |                           ^~~~~~
a.cc:27:2: error: expected ';' after class definition
   27 | }
      |  ^
      |  ;
a.cc: In static member function 'static void Main::main(int*)':
a.cc:5:5: error: 'Scanner' was not declared in this scope
    5 |     Scanner scan = new Scanner(System.in);
      |     ^~~~~~~
a.cc:6:5: error: 'String' was not declared in this scope
    6 |     String name[] = {"black","blue","lime","aqua","red","fuchsia","yellow","white"};
      |     ^~~~~~
a.cc:7:9: error: declaration of 'color' as multidimensional array must have bounds for all dimensions except the first
    7 |     int color[][] = {{0,0,0},{0,0,255},{0,255,0},{0,255,255},{255,0,0},{255,0,255},{255,255,0},{255,255,255}};
      |         ^~~~~
a.cc:9:14: error: expected ';' before 'str'
    9 |       String str = scan.next();
      |              ^~~
a.cc:10:10: error: 'str' was not declared in this scope; did you mean 'std'?
   10 |       if(str.equals("0")) break;
      |          ^~~
      |          std
a.cc:12:15: error: 'Integer' was not declared in this scope
   12 |       int R = Integer.parseInt(str.substring(1,3),16);
      |               ^~~~~~~
a.cc:12:32: error: 'str' was not declared in this scope; did you mean 'std'?
   12 |       int R = Integer.parseInt(str.substring(1,3),16);
      |                                ^~~
      |                                std
a.cc:15:20: error: 'Double' was not declared in this scope; did you mean 'double'?
   15 |       double min = Double.MAX_VALUE;
      |                    ^~~~~~
      |                    double
a.cc:18:23: error: 'Math' was not declared in this scope
   18 |         double near = Math.sqrt(Math.pow(R - color[i][0],2) + Math.pow(G - color[i][1],2) + Math.pow(B - color[i][2],2));
      |                       ^~~~
a.cc:18:46: error: 'color' was not declared in this scope
   18 |         double near = Math.sqrt(Math.pow(R - color[i][0],2) + Math.pow(G - color[i][1],2) + Math.pow(B - color[i][2],2));
      |                                              ^~~~~
a.cc:24:7: error: 'out' was not declared in this scope
   24 |       out.println(name[Index]);
      |       ^~~
a.cc:24:19: error: 'name' was not declared in this scope
   24 |       out.println(name[Index]);
      |                   ^~~~