#include <bits/stdc++.h>
#include <atcoder/all>
#include <boost/polygon/point_data.hpp>
#include <boost/polygon/voronoi.hpp>
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(x) begin(x),end(x)
#define sz(x) (int)(x).size()
using namespace std;
using namespace atcoder;
using ll=long long;
using ull=unsigned long long;
using ld=long double;
using vll=vector<ll>;
using vvll=vector<vll>;
using vi=vector<int>;
using vvi=vector<vi>;
using pll=pair<ll,ll>;
using pi=pair<int,int>;

// using mint=modint998244353;
using mint=modint1000000007;
// using mint2=static_modint<2>;

// using BoostPoint=boost::polygon::point_data<int>;
// using Voronoi=boost::polygon::voronoi_diagram<double>;

// using mint=LazyMontgomeryModInt<998244353>;
using vm=vector<mint>;
using vvm=vector<vm>;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
	//斜めi+j=tを見て素直にdpすれば良い
	int H,W;
	cin>>H>>W;
	vector<string>S(H);
	for(auto&row:S)cin>>row;
	if(H>W){
		vector<string>nS(W,string(H,' '));
		rep(i,0,H)rep(j,0,W)nS[j][i]=S[i][j];
		swap(H,W);
		swap(nS,S);
	}
	int D=H+W-2,m=D/2;
	vvm dp(H,vm(H));
	if(S[0][0]==S[H-1][W-1])dp[0][H-1]=1;
	rep(t,0,m){
		vvm ndp(H,vm(H));
		rep(a,0,H){
			rep(b,0,H){
				if(dp[a][b]==0)continue;
				rep(u,0,2){
					rep(v,0,2){
						int na=a+u,nb=b-v;
						int x=t+1-na,y=D-t-1-nb;
						if(na>=H||nb<0||x<0||x>=W||y<0||y>=W)continue;
						if(S[na][x]!=S[nb][y])continue;
						ndp[na][nb]+=dp[a][b];
					}
				}
			}
		}
		swap(dp,ndp);
	}
	mint ans=0;
	rep(a,0,H){
		ans+=dp[a][a];
		if(D%2&&a+1<H)ans+=dp[a][a+1];
	}
	cout<<ans.val()<<'\n';
}