import sys
import io, os
input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline
n, k = map(int, input().split())
event = []
for i in range(n):
l, r = map(int, input().split())
event.append(2*l)
event.append(2*r+1)
event.sort()
cur = 0
ans = []
for x in event:
if x%2 == 0:
if cur+1 == k and cur < k:
start = x//2
cur += 1
else:
if cur == k and cur-1 < k:
ans.append((start, x//2))
cur -= 1
print(len(ans))
for l, r in ans:
print(l, r)
#include <bits/stdc++.h>
using namespace std;
void __print(int x) {cerr << x;} void __print(long x) {cerr << x;} void __print(long long x) {cerr << x;} void __print(unsigned x) {cerr << x;} void __print(unsigned long x) {cerr << x;} void __print(unsigned long long x) {cerr << x;} void __print(float x) {cerr << x;} void __print(double x) {cerr << x;} void __print(long double x) {cerr << x;} void __print(char x) {cerr << '\'' << x << '\'';} void __print(const char *x) {cerr << '\"' << x << '\"';} void __print(const string &x) {cerr << '\"' << x << '\"';} void __print(bool x) {cerr << (x ? "true" : "false");} template<typename T, typename V> void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';} template<typename T> void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";} void _print() {cerr << "]\n";} template <typename T, typename... V> void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
using ll = long long;
template<typename T> void min_self( T &a, const T b ) { if(b < a) a = b; }
template<typename T> void max_self( T &a, const T b ) { if(b > a) a = b; }
const int inf = (int)1e9 + 7;
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, k;
cin >> n >> k;
vector<array<int, 2>> p(n);
vector<pair<int, int>> events;
for(auto &[x, y] : p){
cin >> x >> y;
events.emplace_back(x, 1);
events.emplace_back(y, -1);
}
#define pii pair<int, int>
sort(events.begin(), events.end(), [&](pii a, pii b){
if(a.first == b.first)
return a.second > b.second;
return a.first < b.first;
});
vector<pair<int, int>> segs;
int m = (int)events.size();
int c = 0;
int who = inf;
for(int i = 0;i < m;i++){
c += events[i].second;
if(c == k - 1 && events[i].second == -1){
assert(who != inf);
segs.emplace_back(who, events[i].first);
who = inf;
}else if(c >= k){
if(who == inf) who = events[i].first;
}
}
cout << (int)segs.size() << "\n";
for(auto [X, Y] : segs){
cout << X << " " << Y << "\n";
}
return 0x0;
}961A - Tetris | 1635B - Avoid Local Maximums |
20A - BerOS file system | 1637A - Sorting Parts |
509A - Maximum in Table | 1647C - Madoka and Childish Pranks |
689B - Mike and Shortcuts | 379B - New Year Present |
1498A - GCD Sum | 1277C - As Simple as One and Two |
1301A - Three Strings | 460A - Vasya and Socks |
1624C - Division by Two and Permutation | 1288A - Deadline |
1617A - Forbidden Subsequence | 914A - Perfect Squares |
873D - Merge Sort | 1251A - Broken Keyboard |
463B - Caisa and Pylons | 584A - Olesya and Rodion |
799A - Carrot Cakes | 1569B - Chess Tournament |
1047B - Cover Points | 1381B - Unmerge |
1256A - Payment Without Change | 908B - New Year and Buggy Bot |
979A - Pizza Pizza Pizza | 731A - Night at the Museum |
742A - Arpa’s hard exam and Mehrdad’s naive cheat | 1492A - Three swimmers |