//*************************************************
//????????                                *
//??????                                    *
//??10?8?                                     *
//************************************************* 
int main()
{
    //??i?n???????????n 
    //????a?b?c???????????????i????? 
    int i, n, a[100], b[100], c[100] = {0};
    cin >> n;
    //?????
    //????start??????????t?????????max?????????? 
    int start = 0, t = 0, max = 0;
    //???i????c[i]?1 
    for(i = 1; i <= n; i++)
    {
      cin >> a[i] >> b[i];
      if((a[i] >= 90 )&& (a[i] <= 140) && (b[i] >= 60) && (b[i] <= 90))
      c[i] = 1;
    }
    //?????????????? 
    for(i = 1; i <= n+1; i++)
       {
            if(c[i] == 0)
            {
                    t = i - start -1;
                    start = i;
            
            if(max < t)
            max=t;
            }
       }
    cout << max;
    
}