//#define _GLIBCXX_DEBUG
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef long double ld;

#define mk make_pair
#define inb push_back
#define X first
#define Y second
#define all(v) v.begin(), v.end()
#define sqr(x) (x) * (x)
#define TIME 1.0 * clock() / CLOCKS_PER_SEC
#define y1 AYDARBOG
//continue break pop_back return

int solve();

int main()
{
	//ios_base::sync_with_stdio(0);
	//cin.tie(0);
#define TASK "lzss"
#ifndef _DEBUG
	//freopen(TASK".in", "r", stdin), freopen(TASK".out", "w", stdout);
#endif
	solve();
#ifdef _DEBUG
	fprintf(stderr, "\nTIME: %.3f\n", TIME);
#endif
}

const int BUFSZ = (int)1e5 + 7;
char buf[BUFSZ];
string get_str()
{
	scanf(" %s", buf);
	return string(buf);
}

int solve()
{
	int n, m;
	scanf("%d %d", &n, &m);
	swap(n, m);
	vector<vi> h(n, vi(m));
	pii st, fn;
	scanf("%d %d", &st.Y, &st.X);
	--st.Y, --st.X;
	scanf("%d %d", &fn.Y, &fn.X);
	--fn.Y, --fn.X;
	for (int i = 0; i < n; ++i)
	{
		for (int j = 0; j < m; ++j)
		{
			scanf("%d", &h[i][j]);
		}
	}
	vector<vi> d(n, vi(m, -1));
	d[st.X][st.Y] = 0;
	queue<pii> q;
	q.push(st);
	while (!q.empty())
	{
		int x = q.front().X;
		int y = q.front().Y;
		q.pop();
		//horr
		{
			int ch = h[x][y] + 1;
			int nx = x;
			int ny = y + 1;
			while (ny < m)
			{
				if (ch >= h[nx][ny])
				{
					if (d[nx][ny] == -1)
					{
						d[nx][ny] = d[x][y] + 1;
						q.push(mk(nx, ny));
					}
				}
				else
				{
					break;
				}
				++ny;
				--ch;
			}
		}
		//horl
		{
			int ch = h[x][y] + 1;
			int nx = x;
			int ny = y - 1;
			while (ny >= 0)
			{
				if (ch >= h[nx][ny])
				{
					if (d[nx][ny] == -1)
					{
						d[nx][ny] = d[x][y] + 1;
						q.push(mk(nx, ny));
					}
				}
				else
				{
					break;
				}
				--ny;
				--ch;
			}
		}
		//veru
		{
			int ch = h[x][y] + 1;
			int nx = x - 1;
			int ny = y;
			while (nx >= 0)
			{
				if (ch >= h[nx][ny])
				{
					if (d[nx][ny] == -1)
					{
						d[nx][ny] = d[x][y] + 1;
						q.push(mk(nx, ny));
					}
				}
				else
				{
					break;
				}
				--nx;
				--ch;
			}
		}
		//verd
		{
			int ch = h[x][y] + 1;
			int nx = x + 1;
			int ny = y;
			while (nx < n)
			{
				if (ch >= h[nx][ny])
				{
					if (d[nx][ny] == -1)
					{
						d[nx][ny] = d[x][y] + 1;
						q.push(mk(nx, ny));
					}
				}
				else
				{
					break;
				}
				++nx;
				--ch;
			}
		}
	}
	if (d[fn.X][fn.Y] == -1)
		puts("IMPOSSIBLE"), exit(0);
	printf("%d\n", d[fn.X][fn.Y]);
	return 0;
}