What's wrong with my if else statement?

I am having a hard time figuring out what's wrong with my code. Here is my code and when i run it it displays the same word all over again even though i entered different numbers. Please help me, thanks a lot.

int main()
{
    const int size = 4;
    double arr[size];
    int i;

    cout << "Input numbers: ";

    for(i=0;i<4;i++)
    {
        cin >> arr[i];
    }

    for(i=0;i<size;i++)
    {
        if(0<=arr[i]<=5)
        {
            cout << "HEY" << endl;
        }
        else if(0>arr[i])
        {
            cout << "Hello" << endl;
        }
        else if(10<arr[i]<20)
        {
            cout << "Haha" << endl;
        }
        else
        {
            cout << "Hoho";
        }

    }

    cin.ignore();   cin.ignore();
    return 0;
}