View Compilation Error

0_0_13904009_13125.cpp:3:2: error: 'set' does not name a type
  set<int> s;
  ^
0_0_13904009_13125.cpp:4:10: error: 'set' does not name a type
  typedef set<int>::iterator IT;
          ^
0_0_13904009_13125.cpp: In function 'int main()':
0_0_13904009_13125.cpp:8:9: error: 'cin' was not declared in this scope
   while(cin>>n)
         ^
0_0_13904009_13125.cpp:15:4: error: 's' was not declared in this scope
    s.clear();
    ^
0_0_13904009_13125.cpp:16:25: error: 'INT_MAX' was not declared in this scope
    s.insert(0);s.insert(INT_MAX);
                         ^
0_0_13904009_13125.cpp:21:6: error: 'IT' was not declared in this scope
      IT it=--s.find(arr1[i]);
      ^
0_0_13904009_13125.cpp:22:9: error: 'it' was not declared in this scope
      if(it==s.begin())
         ^
0_0_13904009_13125.cpp:28:4: error: 'cout' was not declared in this scope
    cout<<"Case "<<++CNT<<":"<<endl;
    ^
0_0_13904009_13125.cpp:28:31: error: 'endl' was not declared in this scope
    cout<<"Case "<<++CNT<<":"<<endl;
                               ^