Làm bằng C++ giúp mình với ạ :)))

#include <iostream>
using namespace std;
unsigned long long int a, dem;
bool xh = false;
int main()
{
    cin >> a;
    while(a >= 500000)
    {
        a -= 500000;
        dem++;
    }
    if (dem != 0)
    {
        cout << "500 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 200000)
    {
        a -= 200000;
        dem++;
    }
    if(xh)
    {
        cout << "\n";
        xh = false;
    }
    if (dem != 0)
    {
        cout << "200 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 100000)
    {
        a -= 100000;
        dem++;
    }
    if(xh)
    {
        cout << "\n";
        xh = false;
    }
    if (dem != 0)
    {
        cout << "100 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 50000)
    {
        a -= 50000;
        dem++;
    }
    if(xh)
    {
        cout << "\n";
        xh = false;
    }
    if (dem != 0)
    {
        cout << "50 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 20000)
    {
        a -= 20000;
        dem++;
    }
    if(xh)
    {
        cout << "\n";
        xh = false;
    }
    if (dem != 0)
    {
        cout << "20 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 10000)
    {
        a -= 10000;
        dem++;
    }
    if(xh)
    {
        cout << "\n";
        xh = false;
    }
    if (dem != 0)
    {
        cout << "10 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 5000)
    {
        a -= 5000;
        dem++;
    }
    if(xh)
    {
        cout << "\n";
        xh = false;
    }
    if (dem != 0)
    {
        cout << "5 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 2000)
    {
        a -= 2000;
        dem++;
    }
    if(xh)
    {
        cout << "\n";
        xh = false;
    }
    if (dem != 0)
    {
        cout << "2 " << dem;
        xh = true;
    }
    dem = 0;
    while(a >= 1000)
    {
        a -= 1000;
        dem++;
    }
    if (dem != 0) cout << "1 " << dem;
    return 0;
}

$#khantaon$