P1589 泥泞路 样例过，0分求调 玄关

#include<bits/stdc++.h>
#define ll long long
using namespace std;
bool a[111111111];
ll n, m, ans;
ll mini = 9999999999, maxj = -1;
int main() {
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		int ii, jj;
		cin >> ii >> jj;
		if (ii <= mini) {
			mini = ii;
		}
		if (jj >= maxj) {
			maxj = jj;
		}
		for (int j = ii; j <= jj; j++) {
			a[j]++;
		}
	}
	for (int i = mini; i <= maxj; i++) {
		if (a[i] == 1) {
			i += m;
			ans++;
		}
	}
//	cout<<mini<<endl<<maxj<<endl;
	cout << ans;
	return 0;
}
//	ios::sync_with_stdio(false);