#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <cassert>
using namespace std;

#define GET_ARG(a,b,c,F,...) F
#define REP3(i,s,e) for (i = s; i <= e; i++)
#define REP2(i,n) REP3 (i,0,(int)(n)-1)
#define REP(...) GET_ARG (__VA_ARGS__,REP3,REP2) (__VA_ARGS__)
#define RREP3(i,s,e) for (i = s; i >= e; i--)
#define RREP2(i,n) RREP3 (i,(int)(n)-1,0)
#define RREP(...) GET_ARG (__VA_ARGS__,RREP3,RREP2) (__VA_ARGS__)
#define DEBUG(x) cerr << #x ": " << x << endl

string f[50];
int dx[] = {1,0,-1,0};
int dy[] = {0,1,0,-1};
bool used[50][50];
int h, w;

void dfs(int y, int x) {
    int i;
    used[y][x] = true;
    REP (i,4) {
        int ny = y + dy[i];
        int nx = x + dx[i];
        if (ny < 0 || ny >= h || nx < 0 || nx >= w) continue;
        if (!used[ny][nx] && abs(f[y][x]-f[ny][nx]) <= 1) {
            dfs(ny,nx);
        }
        ny += dy[i];
        nx += dx[i];
        if (ny < 0 || ny >= h || nx < 0 || nx >= w) continue;
        if (!used[ny][nx] && f[y][x] == f[ny][nx]) {
            dfs(ny,nx);
        }
    }
}

int main(void) {
    int i, sx, sy, gx, gy;
    cin >> h >> w;
    cin >> sy >> sx >> gy >> gx;
    sx--; sy--; gx--; gy--;
    REP (i,h) cin >> f[i];
    dfs(sy,sx);
    if (used[gy][gx])
        puts("YES");
    else
        puts("NO");
    return 0;
}