#include <stdio.h>

#define maxn 40

const int mon[14]={0,
31,29,31,30,31,30,31,31,30,31,30,31,0};

int n,data[maxn][maxn];
double ans;
FILE *f1,*f2;

void run(void)
{
	int m,d,now,max;
	double zan;
	m=1;
	d=0;
	now=0;
	max=0;
	while (!(m==12 && d==31))
	{
		d++;
		if (d>mon[m])
		{
			d=1;
			m++;
		}
		if (data[m][d]==1)
		{
			if (now>max)
				max=now;
			now=0;
		}
		else
			now++;
	}
	if (now>max)
		max=now;
	zan=max*3600*24;
	ans=zan/366;
}

void ini(void)
{
	int i,a,b;
	fscanf(f1,"%d",&n);
	for (i=0;i<n;i++)
	{
		fscanf(f1,"%d%d",&a,&b);
		data[a][b]=1;
	}
}

int main(void)
{
	f1=fopen("heaven.in","r");
	f2=fopen("heaven.out","w");
	ini();
	run();
	fprintf(f2,"%.0lf",ans);
	fclose(f1);fclose(f2);
	return 0;
}