/in/foo.cc: In function 'int main()':
/in/foo.cc:13:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  int l=0,r=n+1,m=l+r>>1;
                  ~^~
/in/foo.cc:19:6: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   m=l+r>>1;
     ~^~
/in/foo.cc: In function 'bool check(int)':
/in/foo.cc:43:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^