// 
// https://yukicoder.me/submissions/118725
// 
// 昔のgetsが火を吹いたため
// 

#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define xprintf(fmt,...) fprintf(stderr,fmt,__VA_ARGS__)
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(auto cnt=0ll;(cnt)<(l);++(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
#define EPS 1e-12
template<typename T1, typename T2> ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }
template<typename iterator> inline size_t argmin(iterator begin, iterator end) { return distance(begin, min_element(begin, end)); }
template<typename iterator> inline size_t argmax(iterator begin, iterator end) { return distance(begin, max_element(begin, end)); }
template<typename T> T& maxset(T& to, const T& val) { return to = max(to, val); }
template<typename T> T& minset(T& to, const T& val) { return to = min(to, val); }

mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
    return uniform_int_distribution<ll>(l, h)(randdev);
}

#ifdef __MAI
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
#ifdef __VSCC
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T> void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        inline MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiblechar(cc); cc = getchar_unlocked());
            for (; isvisiblechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
            return *this;
        }
        template<typename IT> void in(IT begin, IT end) {
            for (auto it = begin; it != end; ++it) *this >> *it;
        }
    };
}
MaiScanner scanner;

string maze[100];

int height, width;
int sx, sy, gx, gy;

int main() {
    int i, j, k, l;

    scanner >> height >> width;

    scanner >> sy >> sx >> gy >> gx; // （ﾟдﾟ）
    sx--; sy--; gx--; gy--;
    
    for (i = 0; i<height; i++) {
        scanner >> (maze[i]);
    }

    queue<array<int,2>> q;
    q.push({sy, sx});

    int x, y, hi;
    while (!q.empty()) {
        auto& v = q.front();
        x = v[1]; y = v[0]; hi = maze[y][x];
        q.pop();

        //printf("%d %d %c\n",x,y,maze[y][x]);

        maze[y][x] = 'g';
        if (y == gy && x == gx) {
            cout << "YES" << endl;
            return 0;
        }

        if (0<x && maze[y][x - 1] != 'g' && abs(maze[y][x - 1] - hi) <= 1) {
            q.push({y, x - 1});
        }
        if (0<y && maze[y - 1][x] != 'g' && abs(maze[y - 1][x] - hi) <= 1) {
            q.push({y - 1, x});
        }
        if (x<width - 1 && maze[y][x + 1] != 'g' && abs(maze[y][x + 1] - hi) <= 1) {
            q.push({y, x + 1});
        }
        if (y<height - 1 && maze[y + 1][x] != 'g' && abs(maze[y + 1][x] - hi) <= 1) {
            q.push({y + 1, x});
        }

        if (1<x && maze[y][x - 2] != 'g' && maze[y][x - 2] == hi && maze[y][x - 1]<hi) {
            q.push({y, x - 2});
        }
        if (1<y && maze[y - 2][x] != 'g' && maze[y - 2][x] == hi && maze[y - 1][x]<hi) {
            q.push({y - 2, x});
        }
        if (x<width - 2 && maze[y][x + 2] != 'g' && maze[y][x + 2] == hi && maze[y][x + 1]<hi) {
            q.push({y, x + 2});
        }
        if (y<height - 2 && maze[y + 2][x] != 'g' && maze[y + 2][x] == hi && maze[y + 1][x]<hi) {
            q.push({y + 2, x});
        }
    }

    // for (y=0;y<height;y++){
    //     for (x=0;x<width;x++){
    //         putchar(maze[y][x]);
    //     }
    //     cout<<endl;
    // }

    cout << "NO" << endl;

    return 0;
}