View Compilation Error

0_0_25615882_7186.cpp: In function 'int main()':
0_0_25615882_7186.cpp:16:3: error: 'b' was not declared in this scope
   b=regex_replace(b,regex("\\.\\*"),"(.)\\1*");
   ^
0_0_25615882_7186.cpp:17:21: error: 'a' was not declared in this scope
         regex_match(a,regex(b))?cout<<"yes"<<endl:cout<<"no"<<endl;
                     ^