#include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <climits>
#include <iostream>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <vector>
#include <sstream>
#include <typeinfo>
#include <fstream>

#define DIV 1000000007
#define MOD 86400
#define RAN 10800

using namespace std;

long long N;
long long ans;


/*
 *範囲の和を取得
 */
//区間[l, r)
struct segtree {
	vector<long long> data;
	long long n;
	segtree(long long nin){
		n = pow( 2, ceil( log(nin) / log(2) ) );
		long long size = 2 * n - 1;
		this->data.resize(size, 0);
	}

	//API for update val
	void update(long long idx, long long val){
		update(idx, val, 0, 0, n);
	}

	long long update(long long idx, long long val, long long node_id, long long left, long long right){
		//if query idx is within range return val
		if( !( left <= idx && idx < right ) ){
			return data[node_id];
		}
		if( left + 1 < right ) {
			//when node range is not 1, get update children val and update node data
			long long mid = (left + right) / 2 ;
			long long L = update(idx, val, 2 * node_id + 1, left, mid);
			long long R = update(idx, val, 2 * node_id + 2, mid, right);
			data[node_id] = L + R;
		} else {
			//when node range is 1, update node data
			data[node_id] = data[node_id] + val;
		}
		return data[node_id];
	}
	
	//API for get value of [l, r)
	long long get(long long l, long long r){
		return get(l, r, 0, 0, n);
	}

	/*
	 *internaly used function
	 *query_l: query left range
	 *query_r: query right range
	 *node_id: node id of 
	 *node_l:  node left range 
	 *node_r:  node right range
	 */
	long long get(long long query_l, long long query_r, long long node_id, long long node_l, long long node_r){
		//query range is outside of node range: return INF
		if( query_r <= node_l || node_r <= query_l ){
			return 0;
		}
		//query range is within node range: return node val
		if( query_l <= node_l && node_r <= query_r ){
			return data[node_id];
		}
		long long mid = (node_l + node_r) / 2;
		long long L = get(query_l, query_r, 2 * node_id + 1, node_l, mid);
		long long R = get(query_l, query_r, 2 * node_id + 2, mid, node_r);
		return L + R;
	}
};




int main(){
	segtree sg(2*MOD + 10);
	cin >> N;
	long long cur = 0;
	for(int i = 0; i < N; i++){
		long long a, b;
		cin >> a >> b;
		cur += a;
		sg.update(cur%MOD, 1);
		sg.update(cur%MOD + MOD, 1);
		cur += b;
		cur %= MOD;
	}
	long long ans = 0;
	for(int s = 0; s + RAN <= 2*MOD; s++){
		ans = max(ans, sg.get(s, s + RAN + 1));
	}
	cout << ans << endl;
}
