#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;
const int DY[] = {-1,0,1,0};
const int DX[] = {0,1,0,-1};

int vis[50][50];
string b[50];
int h, w;

void f(int y, int x){
    if(vis[y][x]++)return;
    int cur = b[y][x];
    rep(i, 4){
        int ny = y + DY[i], nx = x + DX[i];
        if(ny >= 0 && nx >= 0 && ny < h&&nx < w){
            if(abs(cur - b[ny][nx]) <= 1){
                f(ny, nx);
            }
            int nny = y + DY[i] * 2, nnx = x + DX[i] * 2;
            if(cur > b[ny][nx] && nny >= 0 && nnx >= 0 && nny < h&&nnx < w && cur == b[nny][nnx]){
                f(nny, nnx);
            }
        }
    }

}

int main(){
    
    cin >> h >> w;
    int sx, sy, gx, gy;
    cin >> sx >> sy >> gx >> gy;
    --sx; --sy; --gx; --gy;
    rep(y, h){
        cin >> b[y];
    }
    f(sx, sy);
    puts(vis[gx][gy] ? "YES" : "NO");
}