#include<bits/stdc++.h>
using namespace std;
struct node{
	int id,x;
}a[100005];
bool cmp(node f,node s)
{
	return f.x<s.x;
}
unordered_map<int,int>mp;
int n,l=1,r=n,zl=0,ans=INT_MAX;
bool check(int l,int r)
{
	mp.clear();
	int cnt=0;
	for(int i=l;i<=r;i++)
	{
		if(!mp[a[i].id])cnt++;
		mp[a[i].id]=true;
	}
	return cnt==zl;
}
int find(int l,int r)
{
	int mid,l2=l;
	while(l2+1<r)
	{
		int mid=l2+(r-l2)/2;
		if(check(l,mid))r=mid;
		else l2=mid;
	}
	return r;
}
signed main()
{
	cin.tie(0)->sync_with_stdio(0);
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i].x>>a[i].id;
		if(!mp[a[i].id])zl++;
		mp[a[i].id]++;
	}
	sort(a+1,a+1+n,cmp);
	for(int i=1;i<=n;i++)
	{
		int f=find(i,n+1);
		if(f<=n)ans=min(ans,a[f].x-a[i].x);
		else break;
	}
	cout<<ans;
	return 0;
}