#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vint;
typedef pair<int,int> pint;
typedef vector<pint> vpint;
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,n) for(int i=n-1;i>=(0);i--)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
#define all(v) (v).begin(),(v).end()
#define eall(v) unique(all(v), v.end())
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
const int MOD = 1e9 + 7;
const int INF = 1e9;
const ll INFF = 1e18;

int N;
int a[100010], b[100010];
int memo[300000];//累積和

int main(void){
	cin >> N;
	rep(i, N) cin >> a[i] >> b[i];
	int T = 0;
	rep(i, N){
		T += a[i];
		T %= 86400;
		rep(j, 3){
			memo[T + j * 86400]++;
			// printf("%d\n", T + j * 86400);
		}

		T += b[i];
		T %= 86400;
	}
	reps(i, 1, 300000) memo[i] += memo[i - 1];
	// rep(i, 300000)if(memo[i]) printf("%d\n", memo[i]);
	int ans = 0;
	rep(t, 86401){
		int d = memo[t + 14400 + 10800] - memo[t + 14400 - 1];
		chmax(ans, d);
	}
	printf("%d\n", ans);
	return 0;
}