// Exhausted?
// * frank_c1
// * 2017 / 11 / 16

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;

#define lowbit(x) ((x) & (-x))

const int maxn = (int)(2e5) + 5;
int mx[maxn << 2], su[maxn << 2];
vector<int> nxt[maxn];
int n, m;

inline void addX(int x, int v) {
	mx[x] += v; su[x] += v;
}

inline void pd(int x) {
	if (su[x]) {
		addX(x << 1, su[x]); addX(x << 1 | 1, su[x]); su[x] = 0;
	}
}

inline void pu(int x) {
	mx[x] = max(mx[x << 1], mx[x << 1 | 1]);
}

int Q(int x, int l, int r, int p) {
	if (r <= p) return mx[x];
	pd(x); int mid = (l + r) >> 1, ret = Q(x << 1, l, mid, p);
	if (mid < p) ret = max(ret, Q(x << 1 | 1, mid + 1, r, p));
	return ret;
}

void M(int x, int l, int r, int p, int v) {
	if (p <= l) {
		addX(x, v); return;
	} pd(x); int mid = (l + r) >> 1;
	if (p <= mid) M(x << 1, l, mid, p, v); M(x << 1 | 1, mid + 1, r, p, v); pu(x);
}

int main() {
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= n; ++i) {
		int l, r; scanf("%d%d", &l, &r);
		nxt[l].push_back(m - r + 1);
	} int ret = max(0, n - m);
	for (int i = 1; i <= m; ++i) M(1, 0, m, i, -1);
	for (int i = 0; i <= m; ++i) {
		for (int j = 0; j < (int)nxt[i].size(); ++j) M(1, 0, m, nxt[i][j], 1);
		ret = max(ret, Q(1, 0, m, m - i) - i);
	}
	return printf("%d\n", ret), 0;
}