/in/foo.cc: In function 'int main()':
/in/foo.cc:36:11: warning: unused variable 'aaa' [-Wunused-variable]
      char aaa=getchar();
           ^~~
/in/foo.cc:40:15: warning: unused variable 'now' [-Wunused-variable]
      du=0;int now=0;viss=0;ans=0;
               ^~~