How do I solve this error?

<pre>#include <iostream>

using namespace std;

int main()

    int main() {
    int size;
    while (true) {
        cin >> size;
        if (size >=5 && size <=50) {
            break;
        }
    }

    int a[size];

    for (int i = 0; i < size; i++) {
        cin >> a[i];
    }

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

    for (int i = size -1; i > 0; i--) {
        cout << a[i] << ", ";
    }
    cout << endl;

    int b[size];
    for (int i = size -1; i > 0; i--) {
        if (i%2==0) {
            b[i] = a[i] * 2;
        } else {
            b[i] = a[i] * 3;
        }
    }
    for (int i = size -1; i > 0; i--) {
        cout << a[i] << ", ";
    }
    cout << endl;

    int c[size * 2];

    for (int i = 0; i < size; i++) {
        c[i] = a[i] * 2;
    }
    for (int i = 0; i < size; i++) {
        c[i+size] = b[i] * 3;
    }
    for (int i = (size*2) - 1; i > 0; i--) {
        cout << a[i] << ", ";
    }
    cout << endl;

    return 0;
}
}

The error is expected initializer before 'int'. So I programmed many programs like this and it's the first time I'm getting this error. I don't understand why. Can someone please help me?