#include <iostream>
#include <fstream>
#include <queue>

std::ifstream fin("alee.in");
std::ofstream fout("alee.out");

using namespace std;

int a[176][176], n, m, ip1, jp1, ip2, jp2;

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

inline bool Inside(int i, int j)
{
	return i > 0 && i <= n && j > 0 && j <= n;
}

void Fill(int is, int js)
{
	queue<pair<int,int>> Q;
	a[is][js] = 1;
	Q.push({ is, js });
	while (!Q.empty())
	{
		int i, j;
		i = Q.front().first;
		j = Q.front().second;
		for (int k = 0; k < 4; k++)
		{
			int iv, jv;
			iv = i + di[k];
			jv = j + dj[k];
			if (Inside(iv, jv) && a[iv][jv] == 0)
				a[iv][jv] = a[i][j] + 1, Q.push(make_pair(iv, jv));
		}
		Q.pop();
	}

}


int main()
{
	fin >> n >> m;
	for (int i = 1; i <= m; i++)
	{
		int c, b;
		fin >> c >> b;
		a[c][b] = -1;
	}
	fin >> ip1 >> jp1 >> ip2 >> jp2;

	Fill(ip1, jp1);
	fout << a[ip2][jp2];
	return 0;
}