#include <stdio.h>
#include <conio.h>

void main(void)
{
    int user1=200,user2=201,user3=202;
    int pass1=500,pass2=501,pass3=502;
    int enteredUser, enteredPass;

    printf("Please, login,\nID: ");

    while(1)
    {
    scanf("%d", &enteredUser);
    if(enteredUser == user1 || enteredUser == user2 || enteredUser == user3)
        printf("Please, enter your ID: ");
    else
        printf("Unregistered, try again!\n");
    }
    while(3)
    {
    scanf("%d", &enteredPass);
    if(enteredPass == pass1 || enteredPass == pass2 || enteredPass == pass3)
        printf("You are logged in, welcome!\n");
    else
        printf("Wrong password, try again!");
    }

    getch();
}