#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define rrep2(i,n,k) for(int i=n-1;i>=n-k;i--)
#define vll(n,i) vector<long long>(n,i)
#define v2ll(n,m,i) vector<vector<long long>>(n,vll(m,i))
#define v3ll(n,m,k,i) vector<vector<vector<long long>>>(n,v2ll(m,k,i))
#define v4ll(n,m,k,l,i) vector<vector<vector<vector<long long>>>>(n,v3ll(m,k,l,i))
#define all(v) v.begin(),v.end()
#define chmin(k,m) k = min(k,m)
#define chmax(k,m) k = max(k,m)
#define Pr pair<ll,ll>
#define Tp tuple<ll,ll,ll>
#define riano_ std::ios::sync_with_stdio(false);std::cin.tie(nullptr)

#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")

//Graph
struct graph {
    long long N;
	vector<vector<tuple<long long,long long,int>>> G;
    vector<long long> par_v;
    vector<long long> par_e;
    int edge_count = 0;
    
	graph(long long n) {
        N = n;
		G = vector<vector<tuple<long long,long long,int>>>(N);
        par_v = vector<long long>(N,-1);
        par_e = vector<long long>(N,-1);
	}

    void unite(long long a,long long b,long long cost = 1,bool directed = false){
        G[a].emplace_back(b,cost,edge_count);
        if(!directed) G[b].emplace_back(a,cost,edge_count);
        edge_count++;
    }
};

const ll mod = 1e9+7;
template<uint64_t mod>
struct modint{
    uint64_t val;
    constexpr modint(const int64_t val_=0) noexcept:val((val_%int64_t(mod)+int64_t(mod))%int64_t(mod)){}
    constexpr modint operator-() const noexcept{
        return modint(*this)=mod-val;
    }
    constexpr modint operator+(const modint rhs) const noexcept{
        return modint(*this)+=rhs;
    }
    constexpr modint operator-(const modint rhs) const noexcept{
        return modint(*this)-=rhs;
    }
    constexpr modint operator*(const modint rhs) const noexcept{
        return modint(*this)*=rhs;
    }
    constexpr modint operator/(const modint rhs) const noexcept{
        return modint(*this)/=rhs;
    }
    constexpr modint &operator+=(const modint rhs) noexcept{
        val+=rhs.val;
        val-=((val>=mod)?mod:0);
        return (*this);
    }
    constexpr modint &operator-=(const modint rhs) noexcept{
        val+=((val<rhs.val)?mod:0);
        val-=rhs.val;
        return (*this);
    }
    constexpr modint &operator*=(const modint rhs) noexcept{
        val=val*rhs.val%mod;
        return (*this);
    }
    constexpr modint &operator/=(modint rhs) noexcept{
        uint64_t ex=mod-2;
        modint now=1;
        while(ex){
            now*=((ex&1)?rhs:1);
            rhs*=rhs,ex>>=1;
        }
        return (*this)*=now;
    }
    modint & operator++(){
        val++;
        if (val == mod) val = 0;
        return *this;
    }
    modint operator++(int){
        modint<mod> res = *this;
        ++*this;
        return res;
    }
    constexpr bool operator==(const modint rhs) noexcept{
        return val==rhs.val;
    }
    constexpr bool operator!=(const modint rhs) noexcept{
        return val!=rhs.val;
    }
    friend constexpr ostream &operator<<(ostream& os,const modint x) noexcept{
        return os<<(x.val);
    }
    friend constexpr istream &operator>>(istream& is,modint& x) noexcept{
        uint64_t t;
        is>>t,x=t;
        return is;
    }
};
typedef modint<mod> mint;
mint pw(long long a,long long b,long long m = mod){
    if(a%m==0) return mint(0);
    if(b==0) return mint(1);
    else if(b%2==0){
        long long x = pw(a,b/2,m).val;
        return mint(x*x);
    }
    else{
        long long x = pw(a,b-1,m).val;
        return mint(a*x);
    }
}
mint modinv(long long a, long long m = mod) {
    long long b = m, u = 1, v = 0;
    while (b) {
        long long t = a / b;
        a -= t * b; swap(a, b);
        u -= t * v; swap(u, v);
    }
    u %= m;
    return mint(u);
}
#define vm(n,i) vector<mint>(n,i)
#define v2m(n,m,i) vector<vector<mint>>(n,vm(m,i))
#define v3m(n,m,k,i) vector<vector<vector<mint>>>(n,v2m(m,k,i))
#define v4m(n,m,k,l,i) vector<vector<vector<vector<mint>>>>(n,v3m(m,k,l,i))
void out(vector<ll> &v){
    for(ll x:v) cout << x << " ";
    cout << "\n"; return;
}

int main(){
    riano_; mint ans = 0;
    ll N,M,K,H,W,Q,L,R,T; cin >> H >> W;
    char g[H][W];
    rep(i,H){
        rep(j,W) cin >> g[i][j];
    }
    if(g[0][0]!=g[H-1][W-1]){
        cout << 0 << endl; return 0;
    }
    auto dp = v3m((H+W)/2,H,H,0);
    dp[0][0][H-1] = 1;
    rep(i,(H+W)/2-1){
        rep(j,H){
            rep(k,H){
                if(dp[i][j][k]==0) continue;
                rep(l,2){
                    rep(m,2){
                        if(j+l<H&&i-j+1-l<W&&k-1+m>=0&&W-1-i+(H-1-k)-m>=0&&g[j+l][i-j+1-l]==g[k-1+m][W-1-i+(H-1-k)-m]){
                            dp[i+1][j+l][k-1+m] += dp[i][j][k];
                        }
                    }
                }
            }
        }
    }
    // rep(i,(H+W)/2){
    //     rep(j,H){
    //         rep(k,H){
    //             cout << i << " " << j << " " << k << endl;
    //             cout << dp[i][j][k] << endl;
    //         }
    //     }
    // }

    if((H+W)%2==0){
        rep(i,H) ans += dp[(H+W)/2-1][i][i];
    }
    else{
        rep(i,H){
            if((H+W)/2-1-i>=0&&(H+W)/2-i<W&&g[i][(H+W)/2-1-i]==g[i][(H+W)/2-i]){
                ans += dp[(H+W)/2-1][i][i];
            }
            if(i+1<H&&(H+W)/2-1-i>=0&&(H+W)/2-1-i<W&&g[i][(H+W)/2-1-i]==g[i+1][(H+W)/2-1-i]){
                ans += dp[(H+W)/2-1][i][i+1];
            }
        }
    }
    cout << ans << endl;
}