// Arup Guha
// 6/18/2023
// Solution to Kattis Problem: Flipping Patties
// https://open.kattis.com/problems/flippingpatties

using namespace std;
#include <bits/stdc++.h>

int main() {

    // Read in n, initialize frequency array.
    int n, most = 0, d, t;
    cin >> n;
    vector<int> freq(43201);
    for (int i=0; i<43201; i++) freq[i] = 0;

    // Process orders.
    for (int i=0; i<n; i++) {
        cin >> d >> t;

        // Just count down by d, starting at t, 3 times.
        for (int j=0,k=t; j<3; j++,k-=d) {
            freq[k]++;
            most = max(most, freq[k]);
        }
    }

    // Ta da!
    cout << (most+1)/2 << endl;
    return 0;
}