/*
 * ????.cpp
 *
 *  Created on: 2012-10-14
 *      Author: ??
 */

int max (int a,int b)    //??????????????????
{
	return a > b?a:b;
}

int main(){
    int n,a,b,ans;    //ans?????
	int sum = 0;
	cin >>n;
	sum = 0;
    ans = 0;
	for (int i = 1;i <= n;i ++)
	{
		cin >>a >>b;
		if ((a >= 90 &&a <= 140) && (b >= 60 &&b <= 90))
			{sum ++;
		ans = max(ans,sum);}    //?????????ans?
		else sum = 0;        //??????????sum??????

	}
	cout <<ans <<endl;
	return 0;
}