function sumOfArray(input) {
    const stack = [...input];
    let result = 0;
    while (stack.length) {
        const element = stack.pop();
        if (Array.isArray(element)) {
            stack.push(...element);
        } else {
            const num = Number.parseInt(element, 10);
            if (!isNaN(num)) {
                result +=  num;
            }
        }
    }
    return result;
}