/in/foo.cc: In function 'int main()':
/in/foo.cc:38:43: warning: array subscript has type 'char' [-Wchar-subscripts]
  while((tmp=getchar())>=0) unavailable[tmp]=1;
                                           ^
/in/foo.cc:39:41: warning: array subscript has type 'char' [-Wchar-subscripts]
  _for(i,0,length) if(!unavailable[str[i]]) printf("%c",str[i]);
                                         ^