function factorial(n){
    if(n === 0)
        return 1;
    return n * factorial(n - 1);
}

console.log(factorial(8));

function sumOfArrays(arr, n){
    if(n === 0){
        return 0;
    }

    return arr[n - 1] + sumOfArrays(arr, n - 1);
}

console.log(sumOfArrays([1, 2, 3, 4, 5], 5));

function fibo(n){
    if(n < 2){
        return n;
    }
    return fibo(n - 1) + fibo(n - 2);
}

console.log(fibo(5));