/in/foo.cc: In function 'int main()':
/in/foo.cc:15:29: warning: array subscript has type 'char' [-Wchar-subscripts]
         if(isalpha(ch)) a[ch]++;q.push_back(ch);
                             ^
/in/foo.cc:15:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
         if(isalpha(ch)) a[ch]++;q.push_back(ch);
         ^~
/in/foo.cc:15:33: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
         if(isalpha(ch)) a[ch]++;q.push_back(ch);
                                 ^
/in/foo.cc:21:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<q.size();i++) if(isalpha(q[i])) out(q[i]);else putchar(q[i]);
                 ~^~~~~~~~~