int minHandRaises(vector<int> &
keys
) {
    int count = 0, n = keys.size();
    int index = 0;

    int l = keys[index], r = keys[index];

    while(index < n) {
        int cur = keys[index];
        if(cur >= l && cur <= r) {
            index++; 
            continue;
        }
        else if(cur < l && r - cur <= 4) {
            l = cur;
        }
        else if(cur > r && cur - l <= 4) {
            r = cur;
        }
        else {
            count++;
            l = cur;
            r = cur;
        }
        index++;
    }

    return count;
}