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#include <iostream>
using namespace std;
#define MAX_Number 9999
#define MIN_Number 1000

int main()
{
	int Card_NUM = 0;
	int flag = 0;

	cout << "Enter 4 last number of your card:" << endl;
	cin >> Card_NUM;
	while(Card_NUM>9999 || Card_NUM<1000 )
	{
		flag = 1;
		if (flag == 1)
		{
			cout << "error" << endl;
			cin >> Card_NUM;
		}
	}
	
	cout << "Correct" << endl;

	return 0;
}