#include <stdio.h>
#include <stdlib.h>

int main()
{
    int n, x, y,i,m=0,drum1,drum2,aux;

    FILE *in = fopen("srv.in.txt", "rt");
    FILE *out = fopen("srv.out.txt", "wt");
    fscanf(in,"%d", &n);
    for (i = 1; i <= n; i++)
    {
        fscanf(in,"%d", &x);
        fscanf(in, "%d", &y);
        if (x > y)
        {
            aux = x;
            x = y;
            y = aux;
        }
        drum1 = y - x;
        drum2 = 6 - y + x;
        if (drum1 > drum2)
            aux = drum2;
        else
            aux = drum1;
        if (m < aux)
            m = aux;
    }
    fprintf(out,"%d", m);
}