#include<fstream>
#include<queue>

using namespace std;

ifstream cin("alee.in");
ofstream cout("alee.out");

int di[] = { 0,0,1,-1 };
int dj[] = { 1,-1,0,0 };

queue<pair<int, int> >Que;

int matrix[180][180], i, j, m, n, new_i, new_j;
int startx, starty, stopx, stopy;

bool OK(int i, int j)
{
    if (i > 0 && j > 0 && i <= n && j <= n && matrix[i][j] != -1)
        return true;
    return false;
}

void Read()
{
    cin >> n >> m;
    for (i = 1; i <= m; i++)
    {
        int ii, jj;
        cin >> ii >> jj;
        matrix[ii][jj] = -1;
    }
    cin >> startx >> starty;
    cin >> stopx >> stopy;
}

void Lee()
{
    matrix[startx][starty] = 1;
    Que.push(make_pair(startx, starty));
    while (!Que.empty())
    {
        i = Que.front().first;
        j = Que.front().second;
        Que.pop();
        for (int dir = 0; dir < 4; dir++)
        {
            new_i = i + di[dir];
            new_j = j + dj[dir];
            if (OK(new_i, new_j) && matrix[new_i][new_j] < 1)
            {
                matrix[new_i][new_j] = matrix[i][j] + 1;
                Que.push(make_pair(new_i, new_j));
            }
        }
    }
}

int main()
{
    Read();
    Lee();
    cout << matrix[stopx][stopy];
    return 0;
}