View Compilation Error

0_0_21368639_13327.cpp: In function 'int main()':
0_0_21368639_13327.cpp:18:2: error: 'ios' has not been declared
  ios::sync_with_stdio(false);
  ^
0_0_21368639_13327.cpp:23:2: error: 'cin' was not declared in this scope
  cin>>T;
  ^
0_0_21368639_13327.cpp:29:3: error: 'cout' was not declared in this scope
   cout<<ans<<endl;
   ^
0_0_21368639_13327.cpp:29:14: error: 'endl' was not declared in this scope
   cout<<ans<<endl;
              ^