#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,q=0,i;
    int bk[367];
    int main(){ 
        freopen("heaven.in","r",stdin);
        freopen("heaven.out","w",stdout);
    	cin>>n;
    	for(int i=1;i<=n;i++){
    		cin>>a1>>a2;
    		sum=0;
    		p=1;
    		while(p!=a1){
    			sum+=a[p];
    			p+=1;
    		}
    		bk[sum+a2]=1;
    	}
    	sum=0;
    	for(int i=1;i<=366;i++){
    		if(!bk[i]){
    			sum+=1;
    		}
    		else{
    			q=max(q,sum);
    			sum=0;
    		}
    	}
    	q=max(q,sum);
    	double ans=q/366.00*60*60*24;
    	printf("%.0f",ans);
        return 0;
    }