#include <iostream>
using namespace std;
int main(){
long n,a,b,sum=0,max=0;
cin >> n;
for(int i=0;i<n;i++){
cin >> a >> b;
if (a>=90 && a<=140 && b>=60 && b<=90){
sum = sum + 1;
}else{
if (sum > max)
max = sum;
sum = 0;
}
}
if (sum > max)
max = sum;
cout << max << endl;
return 0;
}