#include <bits/stdc++.h>

using namespace std;

const int oo = 0x3f3f3f3f;
const double eps = 1e-9;
const double PI = 2.0 * acos(0.0);


typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<string> vs;

#define sz(c) int((c).size())
#define all(c) (c).begin(), (c).end()
#define FOR(i,a,b) for (int i = (a); i < (b); i++)
#define FORS(i,a,b,s) for (int i = (a); i < (b); i=i+(s))
#define FORD(i,a,b) for (int i = int(b)-1; i >= (a); i--)
#define FORIT(i,c) for (__typeof__((c).begin()) i = (c).begin(); i != (c).end(); i++)


int s[3000];
int ep[3000];
int eu[3000];
int st[3000];

vector<pii> exSt;

int dp[3000][3000];

int main(){
	int n; cin >> n;
	
	map<int,int> events;

	FOR(i,0,n){
		cin >> s[i] >> ep[i] >> eu[i] >> st[i];
		events[s[i]] = i;
	}

	int passed = 0;
	int lastTime = 0;
	int accumulated = 0;

	for (auto [time, exam] : events){
		int timeToStudy = time - lastTime + accumulated;

		if (timeToStudy >= st[exam]){
			passed ++;
			accumulated = timeToStudy - st[exam];
			lastTime = ep[exam];
		} else {
			accumulated += time-lastTime;
			lastTime = eu[exam];
		}
	}

	cout << passed << endl;
}