/in/foo.cc:8:8: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   main(){
        ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:10:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for( int i = 0 ; i < a.length() ; i ++ ){
                        ~~^~~~~~~~~~~~
/in/foo.cc:13:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
       for( int i = 0 ; i < b.length() ; i ++ ){
                        ~~^~~~~~~~~~~~

KeyError('config.ini',)