/in/foo.cc: In function 'void fft(cn*, int, int, int)':
/in/foo.cc:18:53: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
  for(int i=1;i<n;i++)rev[i]=(rev[i>>1]>>1)|((i&1)<<t-1);
                                                    ~^~