#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))

// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD

// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;

int h,w,si,sj,gi,gj;
char height[52][52];
bool po[52][52];

int di[] = {1,0,-1,0};
int dj[] = {0,1,0,-1};
void dfs(int i,int j){
  po[i][j] = true;
  REP(d,4){
    int ni,nj;
    ni = i+di[d];
    nj = j+dj[d];
    if(ni<0||nj<0||ni>=h||nj>=w)continue;
    if(!po[ni][nj] && abs(height[i][j]-height[ni][nj])<=1)dfs(ni,nj);

    if(height[i][j]<height[ni][nj])continue;
    ni += di[d];
    nj += dj[d];
    if(ni<0||nj<0||ni>=h||nj>=w)continue;
    if(!po[ni][nj] && height[i][j]==height[ni][nj])dfs(ni,nj);
  }
}

int main(){
  scanf("%d%d%d%d%d%d",&h,&w,&si,&sj,&gi,&gj);
  --si;--sj;--gi;--gj;
  REP(i,h)scanf("%s",height[i]);
  dfs(si,sj);
  puts(po[gi][gj]?"YES":"NO");
  return 0;
}