What is the Big O time complexity of a loop that iterates until a certain condition is met, where the condition is checked within the loop?

Example :

//...

Scanner scanner = new Scanner(System.in);

int number;

do {

    System.out.print("Enter a positive number: ");

    number = scanner.nextInt();

    } while (number <= 0);

System.out.println("You entered: " + number);

//...