#include<bits/stdc++.h>
using namespace std;
struct node
{
	int a;
	int b;
};
node x[105];
int main()
{
	int maxx=-99999;
	int n;
	int ans=0;
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>x[i].a>>x[i].b;
	for(int i=1;i<=n;i++)
	{
		if(x[i].a>=90 and x[i].a<=140 and x[i].b>=60 and x[i].b<=90)
			ans++;
		else
		{
			if(max(maxx,ans)==ans)
				maxx=ans;
			ans=0;
		}
	}
	cout<<maxx<<endl;
	return 0;
}

算例都过不了QAQ