#include <bits/stdc++.h>
using std::cin;
using std::cout;

typedef std::pair <int, int> pr;
const int N = 10054;

int n, t;
int right[N];
int cur[N], f[N], forbid[N];
pr a[N];

inline void down(int &x, const int y) {x > y ? x = y : 0;}

int main() {
	int i, l, r;
	std::ios::sync_with_stdio(false), cin.tie(NULL);
	cin >> n >> t;
	for (i = 0; i < n; ++i) cin >> l >> r, cur[i] = n - 1, a[i] = pr(l, right[i] = r);
	std::sort(a, a + n), std::sort(right, right + n),
	memset(forbid, 63, n << 2), memcpy(f, right, n << 2);
	for (l = n - 1; l >= 0; --l)
		for (r = n - 1; right[r] >= a[l].second; --r) {
			int &j = cur[r];
			for (f[r] -= t; l < j && f[r] < a[j].first; --j) down(f[r], forbid[j]);
			if (f[r] < a[l].first) return cout << "no\n", 0;
			down(forbid[l], f[r] - t);
		}
	return cout << "yes\n", 0;
}