#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
int yu[1001],s[1001],y[1001];
int main()
{
	int n,sum=0;
	cin>>n; 
	for(int i=1;i<=n;++i){
		cin>>yu[i];
		cin>>s[i];
		cin>>y[i];
	}
	for(int i=1;i<=n;++i){
		if(abs(yu[i]-yu[i+1])<=5&&abs(s[i]-s[i+1])<=5&&abs(y[i]-y[i+1])<=5&&abs((yu[i]+s[i]+y[i])-(yu[i+1]+s[i+1]+y[i+1]))<=10)
		{
			sum++;
		}
	}
	cout<<sum;
	return 0;
}