#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
namespace my{
using ml=atcoder::modint1000000007;
auto&operator>>(istream&i,ml&x){int t;i>>t;x=t;return i;}
auto&operator<<(ostream&o,const ml&x){return o<<(int)x.val();}
#define eb emplace_back
#define done(...) return pp(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;lin(__VA_ARGS__)
#define FO(n) for(ll ij=n;ij-->0;)
#define FOR(i,...) for(auto[i,i##stop,i##step]=range(0,__VA_ARGS__);i<i##stop;i+=i##step)
#define fo(i,...) FO##__VA_OPT__(R)(i __VA_OPT__(,__VA_ARGS__))
#define of(i,...) for(auto[i,i##stop,i##step]=range(1,__VA_ARGS__);i>=i##stop;i-=i##step)
#define fe(a,i,...) for(auto&&__VA_OPT__([)i __VA_OPT__(,__VA_ARGS__]):a)
#define grid_right_down_fe(x,y,nx,ny,H,W) for(ll nx=x,ny=y+1;nx<=x+1;++nx,--ny)if(nx<H&&ny<W)
#define grid_left_up_fe(x,y,nx,ny,H,W) for(ll nx=x,ny=y-1;nx>=x-1;--nx,++ny)if(0<=nx&&0<=ny)
#define single_testcase void solve();}int main(){my::io();my::solve();}namespace my{
void io(){cin.tie(nullptr)->sync_with_stdio(0);cout<<fixed<<setprecision(15);}
using ll=long long;
constexpr auto range(bool s,auto...a){array<ll,3>r{0,0,1};ll I=0;((r[I++]=a),...);if(!s&&I==1)swap(r[0],r[1]);r[0]-=s;return r;}
constexpr char newline=10;
constexpr char space=32;
auto max(const auto&...a){return max(initializer_list<common_type_t<decltype(a)...>>{a...});}
auto min(const auto&...a){return min(initializer_list<common_type_t<decltype(a)...>>{a...});}

template<class A,class B>struct pair{
  A a;B b;
  pair()=default;
  pair(A a,B b):a(a),b(b){}
  pair(const std::pair<A,B>&p):a(p.first),b(p.second){}
  auto operator<=>(const pair&)const=default;
  pair operator+(const pair&p)const{return{a+p.a,b+p.b};}
  friend ostream&operator<<(ostream&o,const pair&p){return o<<p.a<<space<<p.b;}
};

template<class T,class U>ostream&operator<<(ostream&o,const std::pair<T,U>&p){return o<<p.first<<space<<p.second;}
template<class T,class U>ostream&operator<<(ostream&o,const unordered_map<T,U>&m){fe(m,e)o<<e.first<<space<<e.second<<newline;return o;}

template<class V>concept vectorial=is_base_of_v<vector<typename V::value_type>,V>;
template<class T>struct vec_attr{using core_type=T;static constexpr int d=0;};
template<vectorial V>struct vec_attr<V>{using core_type=typename vec_attr<typename V::value_type>::core_type;static constexpr int d=vec_attr<typename V::value_type>::d+1;};
template<class T>using core_t=vec_attr<T>::core_type;
template<class V>istream&operator>>(istream&i,vector<V>&v){fe(v,e)i>>e;return i;}
template<class V>ostream&operator<<(ostream&o,const vector<V>&v){fe(v,e)o<<e<<string(&e!=&v.back(),vectorial<V>?newline:space);return o;}

template<class V>struct vec:vector<V>{
  using vector<V>::vector;
  vec(const vector<V>&v){vector<V>::operator=(v);}

  vec&operator^=(const vec&u){this->insert(this->end(),u.begin(),u.end());return*this;}
  vec operator^(const vec&u)const{return vec{*this}^=u;}
  vec&operator+=(const vec&u){vec&v=*this;fo(i,v.size())v[i]+=u[i];return v;}
  vec&operator-=(const vec&u){vec&v=*this;fo(i,v.size())v[i]-=u[i];return v;}
  vec operator+(const vec&u)const{return vec{*this}+=u;}
  vec operator-(const vec&u)const{return vec{*this}-=u;}
  vec&operator++(){fe(*this,e)++e;return*this;}
  vec&operator--(){fe(*this,e)--e;return*this;}
  vec operator-()const{vec v=*this;fe(v,e)e=-e;return v;}

  auto scan(const auto&f)const{pair<core_t<V>,bool>r{};fe(*this,e)if constexpr(!vectorial<V>)r.b?f(r.a,e),r:r={e,1};else if(auto s=e.scan(f);s.b)r.b?f(r.a,s.a),r:r=s;return r;}
  auto max()const{return scan([](auto&a,const auto&b){a<b?a=b:0;}).a;}
  auto min()const{return scan([](auto&a,const auto&b){a>b?a=b:0;;}).a;}
};

void lin(auto&...a){(cin>>...>>a);}
auto sinen(const string&b="a"){string s;lin(s);vec<ll>r;fe(s,e)r.eb(b.size()==1?e-b[0]:b.find_first_of(e));return r;}
auto sinen(ll n,const string&b="a"){vec<vec<ll>>r;fo(n)r.eb(sinen(b));return r;}
template<char c=space>void pp(const auto&...a){ll n=sizeof...(a);((cout<<a<<string(--n>0,c)),...);cout<<newline;}

ll median_middle_index(ll n){return n/2;}

auto manhattan_distance_dth_enumerate(ll d,ll H,ll W){
  vec<pair<ll,ll>>res;
  fo(i,max(0,d-W+1),min(d,H-1)+1)res.eb(i,d-i);
  return res;
}

ll grid_median_middle(ll H,ll W){return median_middle_index(H+W-1);}

single_testcase
void solve(){
  LL(H,W);
  auto a=sinen(H);

  if(a[0][0]!=a[H-1][W-1])done(0);

  auto index=[&](ll i,ll j,ll k,ll l){return((i*W+j)*H+k)*W+l;};
  unordered_map<ll,ml>dp;
  dp[index(0,0,H-1,W-1)]=1;
  fo(i,H)fo(j,W){
    if(i+j>=grid_median_middle(H,W)+1)continue;
    of(k,H,i)of(l,W,j){
      if((H-1-k)+(W-1-l)>=grid_median_middle(H,W)+1)continue;
      if(i+j!=(H-1-k)+(W-1-l))continue;
      grid_right_down_fe(i,j,ni,nj,H,W){
        grid_left_up_fe(k,l,nk,nl,H,W){
          if(a[ni][nj]==a[nk][nl])dp[index(ni,nj,nk,nl)]+=dp[index(i,j,k,l)];
        }
      }
    }
  }

  ml ans=0;
  if((H+W)&1){
    ll m=(H+W-1)/2-1;
    fe(manhattan_distance_dth_enumerate(m,H,W),i,j)grid_right_down_fe(i,j,ni,nj,H,W)ans+=dp[index(i,j,ni,nj)];
  }else{
    ll m=(H+W)/2-1;
    fe(manhattan_distance_dth_enumerate(m,H,W),i,j)ans+=dp[index(i,j,i,j)];
  }
  pp(ans);
}}