Fold and Sum

function main(lines) {
    nums = lines;

    let nums1 = [];
    let nums2 = [];
    let sum = [];

    let k = nums.length / 4;
    for (let num = k - 1; num >= 0; num--) nums1.push(nums[num]);
    for (let num = k; num < 3 * k; num++) nums2.push(nums[num]);
    for (let num = 4 * k - 1; num >= 3 * k; num--)  nums1.push(nums[num]);
    for (let num = 0; num < 2 * k; num++) {
        let x = parseInt(nums1[num]);
        let y = parseInt(nums2[num]);
        let z = x + y;
        sum.push(z);
    }

    console.log(sum.join(" "));
}

//main(["5", "2", "3", "6"]);