Cpp no match for 'operator<<' for int [closed]

I'm completely new to cpp, and am trying to write a simple Binary Tree. I've done minimal implementation on insert function as below.

#include <iostream>
using namespace std;

template <typename T, typename U>
class MyNode {
    public :
        T key;
        U value;
        MyNode<T,U> * left;
        MyNode<T,U> * right;

        MyNode<T,U>(const T& k, const U& v)
        {
            key = k;
            value = v;
            left = nullptr;
            right = nullptr;
        }
};

template<typename T, typename U>
class MyTree {
    public :
        MyNode<T,U>* root = nullptr;
        bool insert(const T& key, const U& value);

        void check(MyNode<T,U>*& node) {
            if (!node) return;
            std::cout<<node->key<<": "<<node->value<<std::end;
        }
    private :
        bool insert(MyNode<T,U>*& node, const T& key, const U& value);
};

template<typename T, typename U>
bool MyTree<T,U>::insert(const T& key, const U& value) {
    return insert(root, key, value);
}

template<typename T, typename U>
bool MyTree<T,U>::insert(MyNode<T,U>*& node, const T& key, const U& value) {
      if (node == NULL) {
        MyNode<T,U>* newnode;
        newnode->key = key;
        newnode->value = value;
        return true;
      }
      else {
        if (value < node->value) {
          insert(node->left, key, value);
        }
        else {
          insert(node->right, key, value);
        }
      }
}

The main.cpp file below uses the ctest.h file above.

#include <algorithm>
#include <iterator>
#include <vector>
#include <string>
#include <iostream>
#include "ctest.h"

using namespace std;

int main () {
    MyTree<string, int> tree;
    tree.insert("phil", 12);
    tree.check(tree.root);

    return 0;
}

However, when I try to compile the code with command g++ -std=c++11 main.cpp, I'm getting the error below

In file included from main.cpp:6:0:
ctest.h: In instantiation of 'void MyTree<T, U>::check(MyNode<T, U>*&) [with T = std::basic_string<char>; U = int]':
main.cpp:13:22:   required from here
ctest.h:29:43: error: no match for 'operator<<' (operand types are 'std::basic_ostream<char>' and '<unresolved overloaded function type>')
    std::cout<<node->key<<": "<<node->value<<std::end;
                                           ^
ctest.h:29:43: note: candidates are:

The node value's type will be int, as I've defined the tree as MyTree<string, int>, and int type should have the operator <<. Any points I'm missing ? Thank you!