#define _USE_MATH_DEFINES
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <cstring>
#include <queue>
#include <functional>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <math.h>
#include <complex>
#include <cassert>
#define rep(i,a,b) for (int i = (a); i < (b); i++)
#define case(i) cout<<"Case #"<<i<<": "
using namespace std;
typedef long long int ll;
typedef complex<double> com;
const int mod = 1e9 + 7;
const int MOD = 998244353;
const ll INF = 4e18;



int main() {
	int n, k; cin >> n >> k;
	vector<int> sum(k+1, 0);
	rep(i, 0, n) {
		int p1, p2; cin >> p1 >> p2;
		if(p1<k) sum[p1]++;
		if(p2+1<k)sum[p2+1]--;
	}
	int coin = 0,idx=0,s=0;
	while (k > s) {
		coin += sum[idx];
		s += coin;
		idx++;
	}
	cout << idx-1 << endl;
	return 0;
}