#include <bits/stdc++.h>
using namespace std;
#define incII(i, l, r) for(decay_t<decltype(r)> i = (l)    ; i <= (r); i++)
#define incIX(i, l, r) for(decay_t<decltype(r)> i = (l)    ; i <  (r); i++)
#define incXI(i, l, r) for(decay_t<decltype(r)> i = (l) + 1; i <= (r); i++)
#define incXX(i, l, r) for(decay_t<decltype(r)> i = (l) + 1; i <  (r); i++)
#define decII(i, l, r) for(decay_t<decltype(r)> i = (r)    ; i >= (l); i--)
#define decIX(i, l, r) for(decay_t<decltype(r)> i = (r) - 1; i >= (l); i--)
#define decXI(i, l, r) for(decay_t<decltype(r)> i = (r)    ; i >  (l); i--)
#define decXX(i, l, r) for(decay_t<decltype(r)> i = (r) - 1; i >  (l); i--)
#define inc(i, n)  incIX(i, 0, n)
#define dec(i, n)  decIX(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define dec1(i, n) decII(i, 1, n)
auto inII = [](auto a, auto l, auto r) -> bool { return (l <= a && a <= r); };
auto inIX = [](auto a, auto l, auto r) -> bool { return (l <= a && a <  r); };
auto inXI = [](auto a, auto l, auto r) -> bool { return (l <  a && a <= r); };
auto inXX = [](auto a, auto l, auto r) -> bool { return (l <  a && a <  r); };
auto setmin   = [](auto & a, auto b) -> bool { return (b <  a ? a = b, true : false); };
auto setmax   = [](auto & a, auto b) -> bool { return (b >  a ? a = b, true : false); };
auto setmineq = [](auto & a, auto b) -> bool { return (b <= a ? a = b, true : false); };
auto setmaxeq = [](auto & a, auto b) -> bool { return (b >= a ? a = b, true : false); };
using LL = long long int;
using LD = long double;
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define MT make_tuple
#define FI first
#define SE second
#define FR front()
#define BA back()
#define ALL(a) begin(a), end(a)
#define RALL(a) rbegin(a), rend(a)
#define RV(a) reverse(ALL(a))
#define ST(a) sort(ALL(a))
#define RST(a) sort(RALL(a))
#define SC static_cast
#define SI(a) SC<int>(a.size())
#define SL(a) SC<LL>(a.size())
#define RF(e, ...) for(auto && e: __VA_ARGS__)
#define SF(a, ...) for(auto && [__VA_ARGS__]: a)
#define until(e) while(not(e))
#define if_not(e) if(not(e))
#define ef else if
#define UR assert(false)
auto * IS = & cin;
auto * OS = & cout;
template<typename ... A> void in(A & ... a) { (* IS >> ... >> a); }
#define IN(...) __VA_ARGS__; in(__VA_ARGS__)
struct OS_init { OS_init() { * OS << boolalpha << fixed << setprecision(20); } } os_init_;
void                                      out_([[maybe_unused]] string const & s) { }
template<typename A                > void out_([[maybe_unused]] string const & s, A const & a) { * OS << a; }
template<typename A, typename ... B> void out_(                 string const & s, A const & a, B const & ... b) { * OS << a << s; out_(s, b ...); }
auto outF  = [](array<string, 3> const & s, auto const & ... a) { * OS << s[0]; out_(s[1], a ...); * OS << s[2] << flush; };
auto outN  = [](auto const & ... a) { outF({ "", ""  , ""   }, a ...); };
auto outS  = [](auto const & ... a) { outF({ "", " " , " "  }, a ...); };
auto outL  = [](auto const & ... a) { outF({ "", "\n", "\n" }, a ...); };
auto outSN = [](auto const & ... a) { outF({ "", " " , ""   }, a ...); };
auto outNL = [](auto const & ... a) { outF({ "", ""  , "\n" }, a ...); };
auto outSL = [](auto const & ... a) { outF({ "", " " , "\n" }, a ...); };
auto outD  = [](auto const & ... a) { outF({ "[ ", " : " , " ]\n" }, a ...); };
auto out   = outSL;
template<typename A                > void disp_(A const & a) { * OS << a; }
template<typename A, typename ... T> void disp_(A const & a, string const & s, T const & ... t) { string ss; for(auto && e: a) { * OS << ss; ss = s; disp_(e, t ...); } }
auto dispI = [](auto const & a, auto const & s, auto const & ... t) { disp_(a, t ...); * OS << s << flush; };
auto dispT = [](auto const & a, auto const & s, auto const & ... t) { for(auto && e: a) { disp_(e, t ...); * OS << s; } * OS << flush; };
auto dispL = [](auto const & a,                 auto const & ... t) { dispT(a, "\n", t ...); };
template<typename A> istream & operator>>(istream & is, vector<A>       & v) { for(auto && e: v) { is >> e; } return is; }
template<typename A> ostream & operator<<(ostream & os, vector<A> const & v) { string ss; for(auto && e: v) { os << ss << e; ss = " "; } return os; }
template<typename A                > auto make_v(A a) { return a; }
template<typename A, typename ... M> auto make_v(A a, int n, M ... m) { return vector(n, make_v(a, m ...)); }
template<typename A, typename ... N> auto read_v(N ... n) { auto a = make_v(A { }, n ...); in(a); return a; }
template<typename A, size_t N> istream & operator>>(istream & is, array<A, N>       & a) { for(auto && e: a) { is >> e; } return is; }
template<typename A, size_t N> ostream & operator<<(ostream & os, array<A, N> const & a) { string ss; for(auto && e: a) { os << ss << e; ss = " "; } return os; }
template<typename A, typename B> istream & operator>>(istream & is, pair<A, B>       & p) { return is >> p.first >> p.second; }
template<typename A, typename B> ostream & operator<<(ostream & os, pair<A, B> const & p) { return os << p.first << " " << p.second; }
template<int I = 0, typename T> void tin_ (istream & is, T       & t) { if constexpr(I < tuple_size<T>::value) { is >> get<I>(t); tin_<I + 1>(is, t); } }
template<int I = 0, typename T> void tout_(ostream & os, T const & t) { if constexpr(I < tuple_size<T>::value) { if(I != 0) { os << " "; } os << get<I>(t); tout_<I + 1>(os, t); } }
template<typename ... A> istream & operator>>(istream & is, tuple<A ...>       & t) { tin_ (is, t); return is; }
template<typename ... A> ostream & operator<<(ostream & os, tuple<A ...> const & t) { tout_(os, t); return os; }

// ---- ----

template<LL M> class ModInt {
private:
	LL v;
	pair<LL, LL> ext_gcd(LL a, LL b) {
		if(b == 0) { assert(a == 1); return { 1, 0 }; }
		auto p = ext_gcd(b, a % b);
		return { p.SE, p.FI - (a / b) * p.SE };
	}
public:
	ModInt(LL vv = 0) { v = vv; if(abs(v) >= M) { v %= M; } if(v < 0) { v += M; } }
	LL val() { return v; }
	static LL mod() { return M; }
	ModInt inv() { return ext_gcd(M, v).SE; }
	ModInt exp(LL b) {
		ModInt p = 1, a = v; if(b < 0) { a = a.inv(); b = -b; }
		while(b) { if(b & 1) { p *= a; } a *= a; b >>= 1; }
		return p;
	}
	friend bool      operator< (ModInt    a, ModInt   b) { return (a.v <  b.v); }
	friend bool      operator> (ModInt    a, ModInt   b) { return (a.v >  b.v); }
	friend bool      operator<=(ModInt    a, ModInt   b) { return (a.v <= b.v); }
	friend bool      operator>=(ModInt    a, ModInt   b) { return (a.v >= b.v); }
	friend bool      operator==(ModInt    a, ModInt   b) { return (a.v == b.v); }
	friend bool      operator!=(ModInt    a, ModInt   b) { return (a.v != b.v); }
	friend ModInt    operator+ (ModInt    a            ) { return ModInt(+a.v); }
	friend ModInt    operator- (ModInt    a            ) { return ModInt(-a.v); }
	friend ModInt    operator+ (ModInt    a, ModInt   b) { return ModInt(a.v + b.v); }
	friend ModInt    operator- (ModInt    a, ModInt   b) { return ModInt(a.v - b.v); }
	friend ModInt    operator* (ModInt    a, ModInt   b) { return ModInt(a.v * b.v); }
	friend ModInt    operator/ (ModInt    a, ModInt   b) { return a * b.inv(); }
	friend ModInt    operator^ (ModInt    a, LL       b) { return a.exp(b); }
	friend ModInt  & operator+=(ModInt  & a, ModInt   b) { return (a = a + b); }
	friend ModInt  & operator-=(ModInt  & a, ModInt   b) { return (a = a - b); }
	friend ModInt  & operator*=(ModInt  & a, ModInt   b) { return (a = a * b); }
	friend ModInt  & operator/=(ModInt  & a, ModInt   b) { return (a = a / b); }
	friend ModInt  & operator^=(ModInt  & a, LL       b) { return (a = a ^ b); }
	friend istream & operator>>(istream & s, ModInt & b) { s >> b.v; b = ModInt(b.v); return s; }
	friend ostream & operator<<(ostream & s, ModInt   b) { return (s << b.v); }
};
using MI = ModInt<1'000'000'007>;

// ----

int main() {
	int IN(h, w);
	auto ok = [&](int i, int j) -> bool {
		return inIX(i, 0, h) && inIX(j, 0, w);
	};
	const int L = h + w - 1;
	auto s = read_v<string>(h);
	
	auto dp = make_v<MI>(0, L, h, h);
	MI ans = 0;
	(L == 1 ? ans : dp[0].FR.BA) = (s.FR.FR == s.BA.BA ? 1 : 0);
	auto f = [&](int n, int i, int I, int ii, int II) {
		int N = L - 1 - n;
		int nn = n + 1, j = n - i, jj = nn - ii;
		int NN = N - 1, J = N - I, JJ = NN - II;
		if(ok(i, j) && ok(I, J) && ok(ii, jj) && ok(II, JJ) && s[ii][jj] == s[II][JJ]) {
			(MP(ii, jj) == MP(II, JJ) || (MP(ii, jj) == MP(I, J) && MP(II, JJ) == MP(i, j)) ? ans : dp[nn][ii][II]) += dp[n][i][I];
		}
	};
	inc(n, L / 2) {
		inc(i, h) {
		inc(I, h) {
			f(n, i, I, i + 0, I - 0);
			f(n, i, I, i + 0, I - 1);
			f(n, i, I, i + 1, I - 0);
			f(n, i, I, i + 1, I - 1);
		}
		}
	}
	out(ans);
}