import java.util.*;

import java.io.*;

 

class Grasshop {

 

public static void main( String[] args ) throws Exception {

final BufferedReader br = new BufferedReader( new InputStreamReader( System.in ) );

String line = br.readLine();

while ( line != null ) {

String[] p = line.split( " " );

System.out.println( solve( toi(p[0]), toi(p[1]), toi(p[2]) - 1, toi(p[3]) - 1, toi(p[4]) - 1, toi(p[5]) - 1 ) );

line = br.readLine();

}

}

 

private static final class State implements Comparable<State> {

int r; int c; int len;

 

public State( int r, int c, int len ) { this.r = r; this.c = c; this.len = len; }

 

public int compareTo( State s ) {

if ( this.len == s.len ) return 0;

return this.len < s.len ? -1 : 1;

}

}

 

private static final int[] dirr = { -2, -2, -1, -1, 1, 1, 2, 2 };

private static final int[] dirc = { -1, 1, -2, 2, -2, 2, -1, 1 };

 

private static final String solve( final int R, final int C, final int gr, final int gc, final int lr, final int lc ) {

boolean[][] board = new boolean[R][C];

for ( int ri = 0; ri < R; ++ri ) Arrays.fill( board[ri], false );

PriorityQueue<State> pq = new PriorityQueue<State>();

pq.add( new State(gr, gc, 0) );

while ( !pq.isEmpty() ) {

State act = pq.poll();

if ( act.r == lr && act.c == lc ) return Integer.toString(act.len);

 

for ( int i = 0; i < dirr.length; ++i ) {

int nr = act.r + dirr[i];

if ( nr < 0 || nr >= R ) continue;

int nc = act.c + dirc[i];

if ( nc < 0 || nc >= C ) continue;

if ( !board[nr][nc] ) {

board[nr][nc] = true;

pq.add( new State( nr, nc, act.len + 1 ) );

}

}

}

return "impossible";

}

private static final int toi( String s ) { return Integer.parseInt(s); }