function sumList(array, i, val) {
    if (i != undefined && i < array.length) {
        val += array[i];
        i++;
        return sumList(array, i, val);
    } else if (i != undefined && i === array.length) {
        return val;
    } else {
        return sumList(array, 0, 0);
    }
}


function zip(array1, array2) {
    if (array1.length != array2.length) return -1;
    var length = array1.length;
    var result = [];

    for (var i = 0; i < length; i++) {
        result.push(array1[i]);
        result.push(array2[i]);
    }

    return result;
}

function fib100() {

	var right = 0, left = 1;
	var tmp = null, result = [];
	result.push(right); result.push(left);
	for(var i = 0; i < 98; i++) {
		tmp = left;
		left = left + right;
		right = tmp;
		result.push(left);
	}

	return result;
}

function arrange(array) {

	array.sort(function(a, b) {
		a = a.toString();
		b = b.toString();
		if(parseInt(a[0]) > parseInt(b[0])) {
			return -1;
		} else if (parseInt(a[0]) < parseInt(b[0]))	{
			return 1;
		} else {
			return 0;
		}

	});
	return array.join('');
}