/in/foo.cc: In function 'int main()':
/in/foo.cc:112:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 for(int j=0;j<str.size();j++)
             ~^~~~~~~~~~~
/in/foo.cc:73:17: warning: iteration 26 invokes undefined behavior [-Waggressive-loop-optimizations]
         if(vis[i])
            ~~~~~^
/in/foo.cc:72:18: note: within this loop
     for(int i=1;i<=27;++i)
                 ~^~~~