#include <bits/stdc++.h>
using namespace std;
int e;
int main()
{
	int a,c,d,p = 0,n;
	cin >> n;
	int q[n][5] = {0};
	int w[n] = {0};
	for (int i = 0;i <= n - 1;i ++)
	{
		for (int j = 0;j <= 2;j ++)
		{
			cin >> q[i][j];
		}
		a = q[i][0] + q[i][1] + q[i][2];
		q[i][3] = a;
	}
	for (int i = 0;i <= n;i ++)
	{
		w[i] = q[i][0];
	}
	sort(w + 0,w + n - 1);
	for (int i = n;i > 0;-- i)
	{
		w[p] = w[n - 1];
		p ++;
	}
	for (int i = 0;i <= n - 1;i ++)
	{
		c = w[i];
		d = w[i + 1];
		if (abs(c - d) < 5)
		{
			e ++;
		}
	}
	cout << e;
	return 0;
}