Printing a hollow diamond shape inside a square (interactive)

#include <iostream>
#include <iomanip>

int drawDiamond(int, char);

using std::cout;
using std::cin;
using std::endl;
using std::setw;

int main() {
    int size;
    char character;

    back_size:

    cout << "Input the size of the canvas <uint>: ";
    cin >> size;

    if (static_cast<int>(size) < 3) {
        cout << "Enter a number equal to / larger than 3!\n\n";
        goto back_size;
    }

    cout << "Input the character you want to be used <char>: ";
    cin >> character;

    cout << endl;

    return drawDiamond(size, character);
}

int drawDiamond(int size, char character) {
    int i, j, wsize = (size - (size % 2)) / (size / 2);
    int half = size / 2;

    cout << setw(wsize);

    // First half

    for (i = 1; i <= half + 1; i++) {
        for (j = 1; j <= half + 1 - i; j++) {
            cout << setw(wsize) << character;
        }

        for (j = 1; j <= 2 * i - 1; j++) {
            if (j == 1 || j == 2 * i - 1)
                cout << setw(wsize) << character;
            else
                cout << setw(wsize) << ' ';
        }

        for (j = 1; j <= half + 1 - i; j++) {
            cout << setw(wsize) << character;
        }

        cout << endl;
    }

    // Second half

    for (i = half; i >= 1; i--) {
        for (j = 1; j <= half + 1 - i; j++) {
            cout << setw(wsize) << character;
        }

        for (j = 1; j <= 2 * i - 1; j++) {
            if (j == 1 || j == 2 * i - 1)
                cout << setw(wsize) << character;
            else
                cout << setw(wsize) << ' ';
        }

        for (j = 1; j <= half + 1 - i; j++) {
            cout << setw(wsize) << character;
        }

        cout << endl;
    }

    return 0; // Return a uint to the OS
}

// Exunys <3