View Compilation Error

0_0_35286301_14420.cpp:32:17: error: '__gnu_pbds' is not a namespace-name
 using namespace __gnu_pbds;
                 ^
0_0_35286301_14420.cpp:32:27: error: expected namespace-name before ';' token
 using namespace __gnu_pbds;
                           ^
0_0_35286301_14420.cpp:36:1: error: 'tree' does not name a type
 tree <pli,null_type,less<pli>,rb_tree_tag,tree_order_statistics_node_update> S;
 ^