View Compilation Error

0_0_38442197_21132.cpp: In function 'void test()':
0_0_38442197_21132.cpp:3:2: error: 'cout' was not declared in this scope
  cout<<n<<endl;
  ^
0_0_38442197_21132.cpp:3:11: error: 'endl' was not declared in this scope
  cout<<n<<endl;
           ^
0_0_38442197_21132.cpp:6:16: error: 'rand' was not declared in this scope
   int l = rand() % k + 1;
                ^
0_0_38442197_21132.cpp:7:31: error: 'max' was not declared in this scope
   int r = max(l,rand() % k + 1);
                               ^