#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

int n, m;
int l[2000], r[2000], rl[2000], rr[2000];
int cnt[4001];
bool done[2000];

int main() {
	cin >> n >> m;
	REP(i, n) {
		scanf("%d %d", l + i, r + i);
		
		if (l[i] > m - r[i] - 1) {
			int tmp = l[i];
			l[i] = m - r[i] - 1;
			r[i] = m - tmp - 1;
		}
		
		cnt[l[i]]++;
		cnt[r[i] + 1]--;
	}
	
	FOR(i, 1, m) cnt[i] += cnt[i - 1];
	
	bool ans = true;
	REP(i, m) if (cnt[i] > 2) ans = false;
	
	puts(ans ? "YES" : "NO");
	
	return 0;
}