#include<bits/stdc++.h>
using namespace std;
struct cpp1
{
	int x;
	int id;
}cow[50005];
unordered_map<int,int> cnt;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n;
	int len = 50005;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> cow[i].x >> cow[i].id;
		cnt[cow[i].id]++;
	}
     //从小到大排序  方便选取距离短的 
	sort(cow + 1, cow + n + 1, [](const cpp1& a, const cpp1& b) {
        return a.x < b.x;
    });
    deque<int> window; // 单调队列，存储元素的id
    for (int i = 1; i <= n; i++) {
        cnt[cow[i].id]--;
        window.push_back(cow[i].id);

        while (!window.empty() && cnt[window.front()] > 0) {
            cnt[window.front()]--;
            window.pop_front();
        }

        if (window.size() >= 2) {
            len = min(len, cow[i].x - cow[i - window.size() + 1].x);
        }
    }
	cout << len;
	return 0;
}