C++ : Bizarre Numbers Appearing in Output

For my school project, I am supposed to fill an array of 20 with random numbers between (about) -10 and 10. Then, I have to organize these numbers based on whether they are negative, 0, or positive. I am told to finish off the program printing out the original array, as well as the new array.

For some reason, the organized array prints out random (TYPE:long) numbers in some of the spaces. I'm not sure why this is the case. Below is my code:

#include <iostream>
#include <stdlib.h>
#include <time.h>

int main(int argc, const char * argv[]) {
// insert code here...
srand(time(NULL));
int numbers[20], final[20], first = 1, second = 1;

std::cout << "Enter 20 numbers, and without sorting, this program will take them and organize them based on positive, negative, and 0.\n\n";
for(int i = 0; i < 20; i++){
    std::cout << "Enter number " << (i+1) << ": ";
    //std::cin >> numbers[i];
    numbers[i] = (rand()%20 -10);
    std::cout << numbers[i] << std::endl;
}

//Numbers lower than 0
for(int i = 0; i < 20; i++){
    if(numbers[i] < 0){
        final[i] = numbers[i];
        first++;
    }
}
//Numbers equal to 0
for(int i = first; i < 20; i++){
    if(numbers[i] == 0){
        final[i] = numbers[i];
        second++;
    }
}
//Numbers greater than 0
for(int i = second; i < 20; i++){
    if(numbers[i] == 0){
        final[i] = numbers[i];
    }
}

std::cout << "This is your original array: ";
for(int i = 0; i < 20; i++){
    std::cout << numbers[i];
    if(i != 19)
        std::cout << ",";
    std::cout << " ";
    if(i == 19)
        std::cout << std::endl << std::endl << std::endl;
}

std::cout << "This your new, organized, array: ";
for(int i = 0; i < 20; i++){
    std::cout << final[i];
    if(i != 19)
        std::cout << ",";
    std::cout << " ";
    if(i == 19)
        std::cout << std::endl << std::endl << std::endl;
}

system("pause");
return 0;
}

My output is this:

Enter 20 numbers, and without sorting, this program will take them and organize them based on positive, negative, and 0.

Enter number 1: -6
Enter number 2: 0
Enter number 3: -4
Enter number 4: -5
Enter number 5: 0
Enter number 6: -4
Enter number 7: -5
Enter number 8: -5
Enter number 9: -8
Enter number 10: 5
Enter number 11: 0
Enter number 12: -3
Enter number 13: 5
Enter number 14: -5
Enter number 15: 7
Enter number 16: 2
Enter number 17: 9
Enter number 18: 9
Enter number 19: 3
Enter number 20: 2
This is your original array: -6, 0, -4, -5, 0, -4, -5, -5, -8, 5, 0, -3, 5, -5, 7, 2, 9, 9, 3, 2 


This your new, organized, array: -6, 1879110449, -4, -5, 0, -4, -5, -5, -8, 1, 0, -3, 1606416384, -5, 1606423158, 32767, 1606416416, 32767, 1606416416, 32767"

Thank you in advance to all who reply. I really appreciate it.