#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=2167167167167167167;
const int INF=2100000000;
const ll mod=1e9+7;
#define rep(i,a) for (ll i=0;i<a;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}
int H,W;
bool f(int a,int b){
	return a<H&&b<W&&min(a,b)>=0;
}

void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	cin>>H>>W;
	vector<vector<char>> p(H,vector<char>(W));
	rep(i,H) rep(j,W) cin>>p[i][j];
	if(p[0][0]!=p[H-1][W-1]){
		cout<<"0\n";
		return ;
	}
	vector<vector<ll>> dp(H,vector<ll>(H));
	dp[0][H-1]=1;
	rep(i,INF){
		int A=0+i,B=H+W-2-i;/*
		rep(i,H){
			vec_out(dp[i]);
		}
		cout<<endl;*/
		if(abs(A-B)<=1){
			ll ans=0;
			rep(i,H) rep(j,H){
				if(i<=j&&abs(i-j)<=abs(A-B)) ans=(ans+dp[i][j])%mod;
			}
			cout<<ans<<"\n";
			return ;
		}
		vector<vector<ll>> n_dp(H,vector<ll>(H));
		rep(j,H) rep(k,H){
			int a=A-j,b=B-k;
			if(f(j,a)&&f(k,b)){
				rep(l,2) rep(m,2){
					int x=j+1-l,y=a+l;
					int z=k-1+m,w=b-m;
					if(f(x,y)&&f(z,w)){
						if(p[x][y]==p[z][w]){
							n_dp[x][z]=(n_dp[x][z]+dp[j][k])%mod;
						}
					}
				}
			}
		}
		swap(dp,n_dp);
	}
}