made in China

#include <iostream>
#include <vector>
#include <map>
#include <algorithm>

using namespace std;

int main() {
    int n;
    cin >> n;
    
    vector<pair<int, long long>> cows(n); // (种族, 坐标)
    
    for (int i = 0; i < n; ++i) {
        cin >> cows[i].first >> cows[i].second;
    }
    
    // Step 1: Sort cows based on their coordinates
    sort(cows.begin(), cows.end(), [](const pair<int, long long>& a, const pair<int, long long>& b) {
        return a.second < b.second;
    });
    
    // Step 2: Initialize balance map and other variables
    map<int, int> balance_map; // balance -> first occurrence index
    balance_map[0] = -1; // balance 0 at index -1 (before the start)
    
    int balance = 0;
    long long max_length = 0;
    
    // Step 3: Traverse sorted cows
    for (int i = 0; i < n; ++i) {
        if (cows[i].first == 0) { // Breed 0
            balance--;
        } else { // Breed 1
            balance++;
        }
        
        // Check if this balance has been seen before
        if (balance_map.find(balance) != balance_map.end()) {
            // Calculate the length of the balanced interval
            int start_index = balance_map[balance];
            long long interval_length = cows[i].second - cows[start_index + 1].second; // Get the coordinates
            max_length = max(max_length, interval_length);
        } else {
            // If not seen, record the first index of this balance
            balance_map[balance] = i;
        }
    }
    
    // Output the result
    cout << max_length << endl;
    return 0;
}