/in/foo.cc: In function 'void cc(int, int)':
/in/foo.cc:11:19: warning: left operand of comma operator has no effect [-Wunused-value]
  for(int i=l,j=r;i<=r,j>=l;i++,j--){
                  ~^~~
/in/foo.cc:12:22: warning: statement has no effect [-Wunused-value]
   if(a[i]!=b[j]) flag==1;
                  ~~~~^~~