#include <bits/stdc++.h>

using u32 = unsigned;
using i64 = long long;
using u64 = unsigned long long;
using u128 = unsigned __int128;

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);

	int n;
	std::cin >> n;
	std::vector<std::array<int, 2>> a(n + 1);
	for (int i = 1; i <= n; i ++) {
		std::cin >> a[i][0] >> a[i][1];
	}
	std::sort(a.begin() + 1, a.end());
	int r = a[1][1];
	int l = a[1][0];
	for (int i = 2; i <= n; i++) {
		auto [L, R] = a[i];
		if (L <= r) {
			r = std::max(r, R);
			continue;
		}
		std::cout << l << " " << r << "\n";
		l = L;
		r = R;
	}

	std::cout << l << " " << r << "\n";
	
	return 0;
}