#include<bits/stdc++.h>
using namespace std;
int main(){

    int a,b,c,d,maxx = INT_MIN;
    cin>>a;
    for(int i = 1;i <= a;i++){
        cin>>b>>c;
        if(b >= 90 && b <= 140 && c >= 60 && c <= 90){
            d++;
        }
        else if(maxx <= d){
            maxx = d;
            d = 0;
        }
        else{
            d = 0;
        }
    }
    if(d > maxx){
        maxx = d;
    }
    cout<<maxx;
    
    return 0;
}