退役一年没打oi了，脑子不太好勿喷

#include<bits/stdc++.h>
using namespace std;


signed main()
{
	bool bo = 0;
	int n,a,b,sum = 0;
	cin>>n;
	for(int i = 1;i<=n;i++)
	{
		cin>>a>>b;
		if(a>=90 && a<=140 && b>=60 && b<=90)
		{
			if(i == 1||bo == 1) bo = 0,sum++;
			else bo = 1;
		}
	}
	cout<<sum<<endl;
	return 0;
}