#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,b) for(int i=0;i<b;i++)
#define rrep(i,b) for(int i=b-1;i>=0;i--)
#define rep1(i,b) for(int i=1;i<b;i++)
#define repx(i,x,b) for(int i=x;i<b;i++)
#define fore(i,a) for(auto i:a)
#define fore1(i,a) for(auto &i:a)
#define rng(x) (x).begin(), (x).end()
#define rrng(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define fi first
#define se second

using namespace std;
using namespace atcoder;

using ll = long long;
template<typename T> using mpq = priority_queue<T, vector<T>, greater<T>>;
template<typename T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<typename T> bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> ll sumv(const vector<T>&a){ll res(0);for(auto&&x:a)res+=x;return res;}
bool yn(bool a) { if(a) {cout << "Yes" << endl; return 1;} else {cout << "No" << endl; return 0;}}
#define dame { cout << "No" << endl; return 0;}
#define dame1 { cout << -1 << endl; return 0;}
#define test(x) cout << "test" << x << endl;
#define deb(x,y) cout << x << " " << y << endl;
#define deb3(x,y,z) cout << x << " " << y << " " << z << endl;
#define deb4(x,y,z,x2) cout << x << " " << y << " " << z << " " << x2 << endl;
#define out cout << ans << endl;
#define outv fore(yans , ans) cout << yans << "\n";
#define show(x) cerr<<#x<<" = "<<x<<endl;
#define showv(v) {fore(vy , v) {cout << vy << " ";} cout << endl;}
#define showv2(v) fore(vy , v) cout << vy << "\n";
using pll = pair<ll,ll>;
using pil = pair<int,ll>;
using pli = pair<ll,int>;
using pii = pair<int,int>;
using tp = tuple<int ,int ,int>;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
using vb = vector<bool>;
using vpii = vector<pii>;
using vpli = vector<pli>;
using vpll = vector<pll>;
using vpil = vector<pil>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;
using vvs = vector<vector<string>>;
using vvb = vector<vector<bool>>;
using vvpii = vector<vector<pii>>;
using vvpli = vector<vector<pli>>;
using vvpll = vector<vpll>;
using vvpil = vector<vpil>;
using mint = modint1000000007;
using vm = vector<mint>;
using vvm = vector<vector<mint>>;
vector<int> dx={1,0,-1,0,1,1,-1,-1},dy={0,1,0,-1,1,-1,1,-1};
vector<int> dx2={-1,0,-1,0,1,1,-1,-1},dy2={0,-1,0,-1,1,-1,1,-1};
ll gcd(ll a, ll b) { return a?gcd(b%a,a):b;}
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;

int main(){
    int h,w; cin>>h>>w;

    vs s(h);
    rep(i,h) cin>>s[i];


    vvi state(h+w , vi(max(h,w),-INF));
    vector<map<int , int>> mp(h+w);

    vi m(h+w);

    rep(i,h) rep(j,w){
        int k = i + j;
        mp[k][i * w + j] = m[k];
        state[k][m[k]++] = i * w + j;
    }

    int u = (h+w)/2;
    int u2 = max(h,w)*max(h,w);


    vvm dp(u,vm(max(h,w)*max(h,w)));

    rep(i,u){
        int ri = h+w - i - 2;

        if (i == 0){
            if (s[0][0] == s[h-1][w-1]){
                dp[0][0] = 1;
            }else{
                dp[0][0] = 0;
            }

            continue;
        }

        rep(j,max(h,w)) rep(j2,max(h,w)){
            int st = j + j2 * max(h,w);
            if (dp[i-1][st] == 0) continue;

            int x1,y1,x2,y2;

            x1 = state[i-1][j] / w;
            y1 = state[i-1][j] % w;
            x2 = state[ri+1][j2] / w;
            y2 = state[ri+1][j2] % w;

            // deb(x2 ,y2);
            // deb(j ,j2);

            rep(k1,2) rep(k2,2){
                int nx1,nx2,ny1,ny2;
                nx1 = x1 + dx[k1];
                ny1 = y1 + dy[k1];
                nx2 = x2 + dx2[k2];
                ny2 = y2 + dy2[k2];

                if (nx1 < 0 || nx2 < 0) continue;
                if (nx1 > h-1 || nx2 > h-1) continue;
                if (ny1 < 0 || ny2 < 0) continue;
                if (ny1 > w-1 || ny2 > w-1) continue;

                if (s[nx1][ny1] == s[nx2][ny2]){
                    // show(dp[i-1][st].val());
                    // deb(nx1 , ny1);
                    // deb(nx2 , ny2);
                    int cood1 = mp[i][nx1 * w + ny1];
                    int cood2 = mp[ri][nx2 * w + ny2];

                    dp[i][cood1 + cood2 * max(h,w)] += dp[i-1][st];
                }
            }
        }
    }

    mint ans = 0;

    int ri = h+w - u - 1;


    rep(j,max(h,w)) rep(j2,max(h,w)){

        int st = j + j2 * max(h,w);
        if (dp[u-1][st] == 0) continue;

        int x1,y1,x2,y2;
        x1 = state[u-1][j] / w;
        y1 = state[u-1][j] % w;
        x2 = state[ri][j2] / w;
        y2 = state[ri][j2] % w;


        if (x1 < 0 || x2 < 0) continue;
        if (x1 > h-1 || x2 > h-1) continue;
        if (y1 < 0 || y2 < 0) continue;
        if (y1 > w-1 || y2 > w-1) continue;

        int kk = abs(x1 - x2) + abs(y1 - y2);

        if (kk <= 1){
            ans += dp[u-1][st];
        }
    } 
    
    cout << ans.val() << endl;

    return 0;
}