View Compilation Error

0_0_37896632_9642.cpp: In function 'int main()':
0_0_37896632_9642.cpp:9:2: error: 'cin' was not declared in this scope
  cin>>T;
  ^
0_0_37896632_9642.cpp:21:32: error: 'swap' was not declared in this scope
                  swap(a[j],a[k]);
                                ^
0_0_37896632_9642.cpp:38:6: error: 'cout' was not declared in this scope
      cout<<ans<<endl;
      ^
0_0_37896632_9642.cpp:38:17: error: 'endl' was not declared in this scope
      cout<<ans<<endl;
                 ^