#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(int i=0;i<(n);i++)
#define ALL(v) v.begin(),v.end()
#define debug(a) cerr<<#a<<":"<<a<<endl;
#define debug2(a,b) cerr<<"("<<#a<<","<<#b<<"):("<<a<<","<<b<<")"<<endl;
#define debug3(a,b,c) cerr<<"("<<#a<<","<<#b<<","<<#c<<"):("<<a<<","<<b<<","<<c<<")"<<endl;
#define debug4(a,b,c,d) cerr<<"("<<#a<<","<<#b<<","<<#c<<","<<#d<<"):("<<a<<","<<b<<","<<c<<","<<d<<")"<<endl;

template<typename T>
istream& operator>>(istream&is,vector<T>&v){
  for(T&p:v)is>>p;
  return is;
}
template<typename T>
ostream& operator<<(ostream&os,const vector<T>&v){
  if(&os==&cerr)os<<"[";
  for(int i=0;i<v.size();i++){
    os<<v[i];
    if(i+1<v.size())os<<(&os==&cerr?",":" ");
  }
  if(&os==&cerr)os<<"]";
  return os;
}

template<typename T,T MOD=998244353>
struct Mint{
  inline static constexpr T mod = MOD;
  T v;
  Mint():v(0){}
  Mint(signed v):v(v){}
  Mint(long long t){v=t%MOD;if(v<0)v+=MOD;}

  Mint pow(long long k){
    Mint res(1),tmp(v);
    while(k){
      if(k&1)res*=tmp;
      tmp*=tmp;
      k>>=1;
    }
    return res;
  }

  static Mint add_identity(){return Mint(0);}
  static Mint mul_identity(){return Mint(1);}

  Mint inv(){return pow(MOD-2);}

  Mint& operator+=(Mint a){v+=a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator-=(Mint a){v+=MOD-a.v;if(v>=MOD)v-=MOD;return *this;}
  Mint& operator*=(Mint a){v=1LL*v*a.v%MOD;return *this;}
  Mint& operator/=(Mint a){return (*this)*=a.inv();}

  Mint operator+(Mint a) const{return Mint(v)+=a;}
  Mint operator-(Mint a) const{return Mint(v)-=a;}
  Mint operator*(Mint a) const{return Mint(v)*=a;}
  Mint operator/(Mint a) const{return Mint(v)/=a;}

  Mint operator+() const{return *this;}
  Mint operator-() const{return v?Mint(MOD-v):Mint(v);}

  bool operator==(const Mint a)const{return v==a.v;}
  bool operator!=(const Mint a)const{return v!=a.v;}

  static Mint comb(long long n,int k){
    Mint num(1),dom(1);
    for(int i=0;i<k;i++){
      num*=Mint(n-i);
      dom*=Mint(i+1);
    }
    return num/dom;
  }

  friend ostream& operator<<(ostream&os,const Mint &m){os<<m.v;return os;}
  friend istream& operator>>(istream&is,Mint &m){is>>m.v;m.v%=MOD;if(m.v<0)m.v+=MOD;return is;}
};

using mint=Mint<long long,1000000007>;

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

  int h,w;cin>>h>>w;
  vector<string> s(h);
  cin>>s;

  map<pair<int,int>,mint> mp;
  int a=-1,b;
  if((h+w-1)&1){
    REP(i,h)REP(j,w)if((i+1+j+1-1)*2-1 == h+w-1){
      mp[{i,i}]=1;
      a=i+j,b=i+j;
    }
  }
  else{
    REP(i,h)REP(j,w)if((i+1+j+1-1)*2 == h+w-1){
      if(i+1<h and s[i+1][j]==s[i][j])mp[{i,i+1}]=1;
      if(j+1<w and s[i][j+1]==s[i][j])mp[{i,i}]=1;
      a=i+j,b=i+j+1;
    }
  }
  
  if(a<0){
    cout<<0<<endl;
    return 0;
  }

  while(a){
    map<pair<int,int>,mint> nxt;
    for(const auto&[key,val]:mp){
      const auto&[y1,y2] = key;
      int x1=a-y1;
      int x2=b-y2;
      assert(x1>=0 and x2>=0);
      //debug4(y1,x1,y2,x2);
      //debug(val);
      if(x1 and x2+1<w and s[y1][x1-1]==s[y2][x2+1])nxt[{y1,y2}]+=val;
      if(x1 and y2+1<h and s[y1][x1-1]==s[y2+1][x2])nxt[{y1,y2+1}]+=val;
      if(y1 and x2+1<w and s[y1-1][x1]==s[y2][x2+1])nxt[{y1-1,y2}]+=val;
      if(y1 and y2+1<h and s[y1-1][x1]==s[y2+1][x2])nxt[{y1-1,y2+1}]+=val;
    }
    mp=nxt;
    a--;b++;
  }

  assert(a==0 and b==h-1+w-1);

  mint ans=0;
  for(const auto&[key,val]:mp)
    ans+=val;
  cout<<ans<<endl;
}