Debugging techniques

#include <iostream>
using namespace std;

int main()
{
    char card('y'); // for entering the cards in the hand
    int numcards(0), score(0), numace(0); // num cards is total number of cards, score is the total score and numace is the number of aces

    while(card=='Y' || card=='y') // loop to continue scoring hands
    {
        //prompt for number of cards

        cout << "Enter the number of cards in your hand: ";
        cin >> numcards;
        // if number of cards is invalid keep prompting for a valid number
        while(!(numcards<=5 && numcards>=2)) 
        {
            cout << "Number of cards in your hand must be a number between 2 and 5." << endl;
            cout << "Enter the number of cards in your hand: ";
            cin >> numcards;
        }

        for(int i=1; i <= numcards; i++) // loop to enter in cards and score
        {
            cout << "Enter a card (2-9, t, j, k, q, a): ";
            cin >> card;

            if(card == '2')
            {
                score+=2;
            }
            else if(card=='9')
            {
                score+=9;
            }
            else if(card=='t' || card=='T' || card=='j' || card=='J' 
            || card=='q' || card=='Q' || card=='k' || card=='K')
            {
                score+=10;
            }
            else if(card=='a' || card=='A')
            {
                score+=11;
                numace++;
            }
            else
            {
                cout << "Invalid input." << endl;
            }
        }

        for(int n=1; n <= numace; n++) // loop to correctly value the aces in a hand
        {
            if(score>21)
            {
                score-=10;
            }
        }
        // if score is less than or equal to 21 print score otherwise the hand is busted
        if(score <= 21) 
        {
            cout << "Your score is " << score << "." << endl;
        }
        else
        {
            cout << "Busted!" << endl;
        }

        // prompt to score another hand

        cout << "To try again enter y or any other character to quit: ";
        cin >> card;

        }

    return 0;
}