CF612D.The Union of k-Segments

You are given $n$ segments on the coordinate axis Ox and the number $k$ . The point is satisfied if it belongs to at least $k$ segments. Find the smallest (by the number of segments) set of segments on the coordinate axis Ox which contains all satisfied points and no others.

The first line contains two integers $n$ and $k$ ( $1<=k<=n<=10^{6}$ ) — the number of segments and the value of $k$ .

The next $n$ lines contain two integers $l_{i},r_{i}$ ( $-10^{9}<=l_{i}<=r_{i}<=10^{9}$ ) each — the endpoints of the $i$ -th segment. The segments can degenerate and intersect each other. The segments are given in arbitrary order.

First line contains integer $m$ — the smallest number of segments.

Next $m$ lines contain two integers $a_{j},b_{j}$ ( $a_{j}<=b_{j}$ ) — the ends of $j$ -th segment in the answer. The segments should be listed in the order from left to right.