/in/foo.cc: In function 'int main()':
/in/foo.cc:9:12: warning: statement has no effect [-Wunused-value]
   case 1: 3; 5; 7; 8; 10; 12;cout<<"31";break;
            ^
/in/foo.cc:9:15: warning: statement has no effect [-Wunused-value]
   case 1: 3; 5; 7; 8; 10; 12;cout<<"31";break;
               ^
/in/foo.cc:9:18: warning: statement has no effect [-Wunused-value]
   case 1: 3; 5; 7; 8; 10; 12;cout<<"31";break;
                  ^
/in/foo.cc:9:21: warning: statement has no effect [-Wunused-value]
   case 1: 3; 5; 7; 8; 10; 12;cout<<"31";break;
                     ^
/in/foo.cc:9:25: warning: statement has no effect [-Wunused-value]
   case 1: 3; 5; 7; 8; 10; 12;cout<<"31";break;
                         ^
/in/foo.cc:9:29: warning: statement has no effect [-Wunused-value]
   case 1: 3; 5; 7; 8; 10; 12;cout<<"31";break;
                             ^
/in/foo.cc:10:12: warning: statement has no effect [-Wunused-value]
   case 4: 6; 9; 11;cout<<"30";break; 
            ^
/in/foo.cc:10:15: warning: statement has no effect [-Wunused-value]
   case 4: 6; 9; 11;cout<<"30";break; 
               ^
/in/foo.cc:10:19: warning: statement has no effect [-Wunused-value]
   case 4: 6; 9; 11;cout<<"30";break; 
                   ^
/in/foo.cc:12:47: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if((year%4==0 && year%100!=0) || year%400==0 && month==2)
                                   ~~~~~~~~~~~~^~~~~~~~~~~