Having problem with loop!!

I am trying to make an easy program but I have it done except it prints off extra data.

Code:

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while (cin) {
      cout << "Enter an even number: ";
      cin >> num;
  if (num % 2 == 0 && num >= 0)
    cout << "The number " << num
          << " is a positive even number." << endl;
                                                   
    else 
    cout << "The number " << num
          << " is not a positive even number!" << endl;
         
    } // end while

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But when i print it looks like this:

Code:

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Enter an even number: 23
The number 23 is not a positive even number!
Enter an even number: -6
The number -6 is not a positive even number!
Enter an even number: 4
The number 4 is a positive even number.
Enter an even number:

---

As you can see, I only put in 3 numbers but 4 things pop up. How can I prevent this? I am sorry that I am fairly new to this.

Code:

---

while (cin) {
      cout << "Enter an even number: ";
      cin >> num;
  if (num % 2 == 0 && num >= 0)
  {
    cout << "The number " << num
          << " is a positive even number." << endl;
    break;
  }                                                   
    else 
    cout << "The number " << num
          << " is not a positive even number!" << endl;
         
    } // end while

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