#include <iostream>

using namespace std;

int get_numbers(int [], int, int);

const int MAX_SIZE=4;

/*
 * Store numbers in the array.
 *
 * array - array to store the numbers in.
 * size - the size of the array.
 * at - the position to start storing numbers at.
 *
 * Returns next free position in the array.
 */
int get_numbers(int array[], int size, int at){
    int temp;

    // Range check for at.
    // If at is invalid, abort the program.
    if(at>=size || at<0){
            cerr << "Invalid array storage position!" << endl;
            exit(-1);
    }

    do {
        cerr << "Enter in a number (-1 to indicate done): ";
        cin >> temp;

        // If number is valid, store it.
        if(temp>=0) {
            array[at]=temp;

            // Go to the next free position.
            at++;
        }
    }while(at<size && temp>=0);

    return at;
}

int main()
{
    int a[MAX_SIZE];

    // Position to store at.
    int position=0;

    // Last position in the array.
    int last;

    last=get_numbers(a,MAX_SIZE,position);

    for(int i=0;i<last;i++) {
        cout << a[i] << endl;
    }

    cout << "Done one time." << endl;

    last=get_numbers(a,MAX_SIZE,last);

    for(int i=0;i<last;i++) {
        cout << a[i] << endl;
    }

    return 0;
}