#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)
#define unless(p) if(!(p))
#define until(p) while(!(p))

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int H, W;
int sx, sy, gx, gy;
string bs[60];

bool used[60][60];

bool dfs(int x, int y){
    used[y][x] = true;
    
    if(x == gx && y == gy){
        return true;
    }

    for(int i=0;i<4;++i){
        int nx = x + dx[i], ny = y + dy[i];
        
        if(nx < 0 || nx >= W || ny < 0 || ny >= H){
            continue;
        }
        if(!used[ny][nx] && abs(bs[ny][nx] - bs[y][x]) <= 1){
            if(dfs(nx, ny)){
                return true;
            }
        }
    }

    for(int i=0;i<4;++i){
        int nx = x + dx[i], ny = y + dy[i];
        int nx2 = nx + dx[i], ny2 = ny + dy[i];
        
        if(nx2 < 0 || nx2 >= W || ny2 < 0 || ny2 >= H){
            continue;
        }
        if(!used[ny2][nx2] && bs[ny2][nx2] == bs[y][x] && bs[ny][nx] < bs[y][x]){
            if(dfs(nx2, ny2)){
                return true;
            }
        }
    }
    
    return false;
}

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    std::cin >> H >> W;
    std::cin >> sx >> sy >> gx >> gy;

    --sx; --sy; --gx; --gy;
    swap(sx, sy);
    swap(gx, gy);
    
    for(int i=0;i<H;++i){
        std::cin >> bs[i];
    }

    bool can = dfs(sx, sy);
    const string YESNO[2] = {"NO", "YES"};
    std::cout << YESNO[can] << std::endl;
}