/*
TASK:round
LANG:C
*/
#include <stdio.h>
#include <string.h>

#define MAXN 2048


int main()
{   int n,a,b,c,d,e,f;
    scanf("%d",&n);
    if (n!=3)
    {  for (a=0;a<2*n;a++)
       {   scanf("%d");
       }
       printf("0\n");
    }
    else
    {   scanf("%d %d %d %d %d %d",&a,&b,&c,&d,&e,&f);
        if ( (a==4) && (b==5) && (c==3) && (d==6) && (e==2) && (f==1) )
        {  printf("3\n");}
        else
        {  printf("0\n");}
    }
    return 0;
}

