#include<iostream>  
#include<cstdio>
#include<cmath>  
#include<cstring>  
#include<algorithm>
using namespace std;
int a[13]={0,31,29,31,30,31,30,31,31,30,31,30,31};
int n,a1,a2,sum,p,ma=0;
int ju[367];
int main(){ 
    freopen("heaven.in","r",stdin);
    freopen("heaven.out","w",stdout);
	cin>>n;
	if(n==0){
		cout<<86400;
		return 0;
	}
	for(int i=1;i<=n;i++){
		cin>>a1>>a2;
		sum=0,p=1;
		while(p!=a1){
			sum+=a[p];
			p+=1;
		}
		ju[sum+a2]=1;
	}
	sum=0;
	for(int i=1;i<=366;i++){
		if(!ju[i]){
			sum+=1;
		}
		else{
			ma=max(ma,sum);
			sum=0;
		}
	}
	ma=max(ma,sum);
	double miao=ma/366.00*60*60*24;
	printf("%.0f",miao);
    return 0;
}