#include <stdio.h>

int q[6000000][3];

int main()
{
	int i, H, W, s[2], g[2];
	char A[1002][1002] = {};
	scanf("%d %d", &H, &W);
	scanf("%d %d", &(s[0]), &(s[1]));
	scanf("%d %d", &(g[0]), &(g[1]));
	for (i = 1; i <= H; i++) scanf("%s", &(A[i][1]));
	
	const int sup = 1 << 30;
	int j, k, l, dist[6][1001][1001], head, tail;
	for (k = 0; k < 6; k++) for (i = 1; i <= H; i++) for (j = 1; j <= W; j++) dist[k][i][j] = sup;
	dist[0][s[0]][s[1]] = 0;
	q[0][0] = 0;
	q[0][1] = s[0];
	q[0][2] = s[1];
	for (head = 0, tail = 1; head < tail; head++) {
		k = q[head][0];
		i = q[head][1];
		j = q[head][2];
		
		if (A[i-1][j] == '.') {
			switch (k) {
			case 0:
				l = 1;
				break;
			case 1:
				l = 5;
				break;
			case 2:
				l = 2;
				break;
			case 3:
				l = 0;
				break;
			case 4:
				l = 4;
				break;
			case 5:
				l = 3;
				break;
			}
			if (dist[l][i-1][j] == sup) {
				dist[l][i-1][j] = dist[k][i][j] + 1;
				q[tail][0] = l;
				q[tail][1] = i - 1;
				q[tail++][2] = j;
			}
		}
		if (A[i+1][j] == '.') {
			switch (k) {
			case 0:
				l = 3;
				break;
			case 1:
				l = 0;
				break;
			case 2:
				l = 2;
				break;
			case 3:
				l = 5;
				break;
			case 4:
				l = 4;
				break;
			case 5:
				l = 1;
				break;
			}
			if (dist[l][i+1][j] == sup) {
				dist[l][i+1][j] = dist[k][i][j] + 1;
				q[tail][0] = l;
				q[tail][1] = i + 1;
				q[tail++][2] = j;
			}
		}
		if (A[i][j-1] == '.') {
			switch (k) {
			case 0:
				l = 4;
				break;
			case 1:
				l = 1;
				break;
			case 2:
				l = 0;
				break;
			case 3:
				l = 3;
				break;
			case 4:
				l = 5;
				break;
			case 5:
				l = 2;
				break;
			}
			if (dist[l][i][j-1] == sup) {
				dist[l][i][j-1] = dist[k][i][j] + 1;
				q[tail][0] = l;
				q[tail][1] = i;
				q[tail++][2] = j - 1;
			}
		}
		if (A[i][j+1] == '.') {
			switch (k) {
			case 0:
				l = 2;
				break;
			case 1:
				l = 1;
				break;
			case 2:
				l = 5;
				break;
			case 3:
				l = 3;
				break;
			case 4:
				l = 0;
				break;
			case 5:
				l = 4;
				break;
			}
			if (dist[l][i][j+1] == sup) {
				dist[l][i][j+1] = dist[k][i][j] + 1;
				q[tail][0] = l;
				q[tail][1] = i;
				q[tail++][2] = j + 1;
			}
		}
	}
	if (dist[0][g[0]][g[1]] == sup) printf("-1\n");
	else printf("%d\n", dist[0][g[0]][g[1]]);
	fflush(stdout);
	return 0;
}