#pragma GCC optimize("O3")
#include<bits/stdc++.h> 
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
// const ll mod=998244353;
const ll mod=1000000007;
const vector<int> dy={-1,0,1,0},dx={0,-1,0,1};
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}} __init;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T>void debag(const vector<T> &a){cerr<<"debag :";for(auto v:a)cerr<<v<<" ";cerr<<"\n";}
template<class T>void print(const vector<T> &a){for(auto v:a)cout<<v<<" ";cout<<"\n";}
struct mint{
using ull=unsigned long long int;
ull v;
mint(ll vv=0){s(vv%mod+mod);}
mint& s(ull vv){
v=vv<mod?vv:vv-mod;
return *this;
}
//オーバーロード
mint operator-()const{return mint()-*this;}//mint型にキャスト
mint&operator+=(const mint&val){return s(v+val.v);}
mint&operator-=(const mint&val){return s(v+mod-val.v);}
mint&operator*=(const mint&val){
v=ull(v)*val.v%mod;
return *this;
}
mint&operator/=(const mint&val){return *this*=val.inv();}
mint operator+(const mint&val){return mint(*this)+=val;}
mint operator-(const mint&val){return mint(*this)-=val;}
mint operator*(const mint&val){return mint(*this)*=val;}
mint operator/(const mint&val){return mint(*this)/=val;}
mint pow(ll n)const{
mint res(1),x(*this);
while(n){
if(n&1)res*=x;
x*=x;
n>>=1ll;
}
return res;
}
mint inv()const{return pow(mod-2);}
//拡張ユークリッドの互除法
/* mint inv()const{
int x,y;
int g=extgcd(v,mod,x,y);
assert(g==1);
if(x<0)x+=mod;
return mint(x);
}*/
friend ostream& operator<<(ostream&os,const mint&val){
return os<<val.v;
}//出力
bool operator<(const mint&val)const{return v<val.v;}
bool operator==(const mint&val)const{return v==val.v;}
bool operator>(const mint&val)const{return v>val.v;}
};
int main(){
    int h,w;
    cin>>h>>w;
    V<string> s(h);
    for(int i=0;i<h;i++)cin>>s[i];
    map<pair<int,int>,int> id;
    int num=0;
    for(int i=0;i<h;i++){
        for(int j=0;j<w;j++){
            for(int k=i;k<h;k++){
                for(int r=j;r<w;r++){
                    if(i+j+k+r==h+w-2)id[{i*w+j,k*w+r}]=num++;
                }
            }
        }
    }
    V<mint> res(num+1,mint(0));
    V<bool> used(num+1,false);
    auto dfs=[&](auto &&self,int a,int b,int c,int d)->mint{
        if(s[a][b]!=s[c][d])return mint(0);
        if(abs(a-c)+abs(b-d)<=1)return mint(1);
        int idx=id[{a*w+b,c*w+d}];
        if(used[idx])return res[idx];
        used[idx]=true;
        mint v=mint(0);
        if(a+1<h){
            if(c-1>=0&&a+1<=c-1)v+=self(self,a+1,b,c-1,d);
            if(d-1>=0&&b<=d-1)v+=self(self,a+1,b,c,d-1);
        }
        if(b+1<w){
            if(c-1>=0&&a<=c-1)v+=self(self,a,b+1,c-1,d);
            if(d-1>=0&&b+1<=d-1)v+=self(self,a,b+1,c,d-1);          
        }
        return res[idx]=v;
    };
    cout<<dfs(dfs,0,0,h-1,w-1)<<"\n";
}