function collapse(array) {
    let l = array.length, i = 0, arr = [], item = [];
    while (l--) {
        const curr = array[i];
        const next = array[i + 1];
        item.length === 0 && item.push(curr);
        if (curr !== next - 1) {
            item.length === 1 && item.push(curr);
        }
        if (item.length === 2) {
            arr.push(item.slice());
            item = [];
        }
        i++;
    }
    return arr;
}


function changeRng(rng, notInRange) {
    const newRng = [];
    const start = notInRange[0];
    const end = notInRange[1];
    let l = rng.length, i = 0;
    while (l--) {
        const rr = rng[i++];
        rr[1] < start && newRng.push(rr);
        if (rr[1] > start && rr[0] < start) {
            newRng.push([rr[0], start - 1]);
            rr[1] > end && newRng.push([end + 1, rr[1]]);
        }
        rr[0] > end && newRng.push(rr);
    }
    return newRng;
}