include<bits/stdc++.h>

using namespace std;

int main() {

int n;
cin>>n;
int max = 0,max_ = 0;
for(int i = 0;i<n;i++)
{
	int x,y;
	cin>>x>>y;
	if(x>=90&&x<=140&&y>=60&&y<=90)
	{
		max_++;
	}
	else
	{
		if(max_>max)max = max_;
		max_=0;
	}
}
cout<<max;
return 0;

}