Main.cc:8:2: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type]
    8 |  main() {
      |  ^~~~
Main.cc: In function ‘int main()’:
Main.cc:19:9: error: expected ‘:’ before ‘;’ token
   19 |   case 4;cout<<30;
      |         ^
      |         :
Main.cc:20:9: error: expected ‘:’ before ‘;’ token
   20 |   case 5;cout<<31;
      |         ^
      |         :
Main.cc:21:9: error: expected ‘:’ before ‘;’ token
   21 |   case 6;cout<<30;
      |         ^
      |         :
Main.cc:22:9: error: expected ‘:’ before ‘;’ token
   22 |   case 7;cout<<31;
      |         ^
      |         :
Main.cc:23:9: error: expected ‘:’ before ‘;’ token
   23 |   case 8;cout<<31;
      |         ^
      |         :
Main.cc:24:9: error: expected ‘:’ before ‘;’ token
   24 |   case 9;cout<<30;
      |         ^
      |         :
Main.cc:25:10: error: expected ‘:’ before ‘;’ token
   25 |   case 10;cout<<31;
      |          ^
      |          :
Main.cc:26:10: error: expected ‘:’ before ‘;’ token
   26 |   case 11;cout<<30;
      |          ^
      |          :
Main.cc:27:10: error: expected ‘:’ before ‘;’ token
   27 |   case 12;cout<<31;
      |          ^
      |          :