made in CHINA

using namespace std;
const int N = 5e4+5;
struct node{
	int x,id;
}a[N];
int cmp(node a,node b)
{
	return a.x<b.x;
}
int main()
{
	int n,s[N]={},ans=0;
	cin>>n;
	for (int i =1;i <=n;i++) 
	{
    	cin >> a[i].id>>a[i].x; 
		if(a[i].id==0)  
		{
			a[i].id=-1;
		}     
	}
	sort(a+1,a+n+1,cmp);

	for (int i =1;i <=n;i++) 
	{
    	s[i]=s[i-1]+a[i].id;     
	}
	for (int i =1;i <=n;i++)
	{
		for (int j=i+1;j<=n;j++)
		{
			if (s[i-1]==s[j])
			{
				ans=max(ans,a[j].x-a[i].x);
			}
		}
	}
	cout << ans;
}