/in/foo.cc: In function 'int main()':
/in/foo.cc:31:8: warning: unused variable 'k' [-Wunused-variable]
  int t,k,root;
        ^
/in/foo.cc:31:10: warning: 'root' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int t,k,root;
          ^~~~