Language: C++

#include <stdio.h>

int main(){
  int X;
    int Y;

  
  switch(scanf()){
   case:A
     X = 10;
      break;
   case:B
     X = 11;
      break;
   case:C
     X = 12;
      break;
   case:D
     X = 13;
      break;
   case:E
     X = 14;
      break;
   case:F
     X = 15;
      break;
  }
  
  switch(scanf()){
   case:A
     Y = 10;
      break;
   case:B
     Y = 11;
      break;
   case:C
     Y = 12;
      break;
   case:D
     Y = 13;
      break;
   case:E
     Y = 14;
      break;
   case:F
     Y = 15;
      break;
  }
  
  int d = X-Y;
  
  if(d > 0){
    println(">");
  }
  else if(d < 0){
    println("<");
  }
  else if(d = 0){
  println("=");
  }
  retrun();
}

Compiler output:
a.cc: In function 'int main()':
a.cc:8:15: error: too few arguments to function 'int scanf(const char*, ...)'
    8 |   switch(scanf()){
      |          ~~~~~^~
In file included from /usr/include/features.h:523,
                 from /usr/include/x86_64-linux-gnu/bits/libc-header-start.h:33,
                 from /usr/include/stdio.h:28,
                 from a.cc:1:
/usr/include/stdio.h:445:12: note: declared here
  445 | extern int __REDIRECT (scanf, (const char *__restrict __format, ...),
      |            ^~~~~~~~~~
a.cc:9:8: error: expected primary-expression before ':' token
    9 |    case:A
      |        ^
a.cc:9:9: error: 'A' was not declared in this scope
    9 |    case:A
      |         ^
a.cc:12:8: error: expected primary-expression before ':' token
   12 |    case:B
      |        ^
a.cc:12:9: error: 'B' was not declared in this scope
   12 |    case:B
      |         ^
a.cc:15:8: error: expected primary-expression before ':' token
   15 |    case:C
      |        ^
a.cc:15:9: error: 'C' was not declared in this scope
   15 |    case:C
      |         ^
a.cc:18:8: error: expected primary-expression before ':' token
   18 |    case:D
      |        ^
a.cc:18:9: error: 'D' was not declared in this scope
   18 |    case:D
      |         ^
a.cc:21:8: error: expected primary-expression before ':' token
   21 |    case:E
      |        ^
a.cc:21:9: error: 'E' was not declared in this scope
   21 |    case:E
      |         ^
a.cc:24:8: error: expected primary-expression before ':' token
   24 |    case:F
      |        ^
a.cc:24:9: error: 'F' was not declared in this scope
   24 |    case:F
      |         ^
a.cc:29:15: error: too few arguments to function 'int scanf(const char*, ...)'
   29 |   switch(scanf()){
      |          ~~~~~^~
/usr/include/stdio.h:445:12: note: declared here
  445 | extern int __REDIRECT (scanf, (const char *__restrict __format, ...),
      |            ^~~~~~~~~~
a.cc:30:8: error: expected primary-expression before ':' token
   30 |    case:A
      |        ^
a.cc:30:9: error: 'A' was not declared in this scope
   30 |    case:A
      |         ^
a.cc:33:8: error: expected primary-expression before ':' token
   33 |    case:B
      |        ^
a.cc:33:9: error: 'B' was not declared in this scope
   33 |    case:B
      |         ^
a.cc:36:8: error: expected primary-expression before ':' token
   36 |    case:C
      |        ^
a.cc:36:9: error: 'C' was not declared in this scope
   36 |    case:C
      |         ^
a.cc:39:8: error: expected primary-expression before ':' token
   39 |    case:D
      |        ^
a.cc:39:9: error: 'D' was not declared in this scope
   39 |    case:D
      |         ^
a.cc:42:8: error: expected primary-expression before ':' token
   42 |    case:E
      |        ^
a.cc:42:9: error: 'E' was not declared in this scope
   42 |    case:E
      |         ^
a.cc:45:8: error: expected primary-expression before ':' token
   45 |    case:F
      |        ^
a.cc:45:9: error: 'F' was not declared in this scope
   45 |    case:F
      |         ^
a.cc:53:5: error: 'println' was not declared in this scope; did you mean 'printf'?
   53 |     println(">");
      |     ^~~~~~~
      |     printf
a.cc:56:5: error: 'println' was not declared in this scope; did you mean 'printf'?
   56 |     println("<");
      |     ^~~~~~~
      |     printf
a.cc:59:3: error: 'println' was not declared in this scope; did you mean 'printf'?
   59 |   println("=");
      |   ^~~~~~~
      |   printf
a.cc:61:3: error: 'retrun' was not declared in this scope
   61 |   retrun();
      |   ^~~~~~