/in/foo.cc: In function 'int main()':
/in/foo.cc:7:10: warning: comparison of constant '1000' with boolean expression is always true [-Wbool-compare]
  int(2<=n<1000);
      ~~~~^~~~~
/in/foo.cc:7:7: warning: comparisons like 'X<=Y<=Z' do not have their mathematical meaning [-Wparentheses]
  int(2<=n<1000);
      ~^~~
/in/foo.cc:7:2: warning: statement has no effect [-Wunused-value]
  int(2<=n<1000);
  ^~~~~~~~~~~~~~