/*????????????????????????90 - 140????????60 - 90????????????????
 * ?????????????????????????????????
 *????: 2012-10-15
 *??: ??
 */

int main ()
{
	int n, time[99], k = 0;       //time?????????????????
	memset(time, 0, sizeof(time));         //??????????0
	cin >> n;
	int high[n], low[n];
	for(int i = 0; i < n; i++)
		{cin >> high[i] >> low[i];
		if(high[i] >= 90 && high[i] <= 140 && low[i] >= 60 && low[i] <= 90)  //??????????+1????????????
			time[k]++;
		else
			k++;
		}
	int maxt = time[0];
	for(int j = 1; j <= k; j++)        //?maxt????????????
		if(time[j] > maxt)
			maxt = time[j];
	cout << maxt;
}
