#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,a[1100],b[1100],c[1100],sum=1;
	cin>>n;
    for(int i=1;i<=n;i++)
    {
    	cin>>a[n]>>b[n]>>c[n];
	}
	for(int i=1;i<=n;i++)
	{
		if(abs(a[i]-a[i-1]<=5)&&abs(b[i]-b[i-1]<=5)&&abs(c[i]-c[i-1]<=5)&&abs((a[i]+b[i]+c[i])-(a[i-1]+b[i-1]+c[i-1])))
		{
			sum++;
		}
	}
	cout<<sum;
    
	return 0;
 }