View Compilation Error

0_0_27728911_8074.cpp: In function 'int main()':
0_0_27728911_8074.cpp:13:40: error: 'a' was not declared in this scope
         while (!sta.empty()) sta.pop();a
                                        ^
0_0_27728911_8074.cpp:27:17: error: 'ans' was not declared in this scope
                 ans--;
                 ^
0_0_27728911_8074.cpp:31:37: error: 'ans' was not declared in this scope
             else if(c == sta.top()) ans--;
                                     ^
0_0_27728911_8074.cpp:42:25: error: 'ans' was not declared in this scope
                         ans--;
                         ^
0_0_27728911_8074.cpp:47:37: error: 'ans' was not declared in this scope
         printf("Case %d: %d\n",kase,ans);
                                     ^