import std.stdio, std.conv, std.functional, std.string;
import std.algorithm, std.array, std.container, std.range, std.typecons;
import std.bigint, std.numeric, std.math, std.random;
import core.bitop;

string FMT_F = "%.10f";

static File _f;
void file_io(string fn) { _f = File(fn, "r"); }
static string[] s_rd;
T _RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; }
T _RD(T = long)(File f) { while(!s_rd.length) s_rd = f.readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; }
T[] _RDA(T = long)(T fix = 0) { auto r = readln.chomp.split.to!(T[]); r[] += fix; return r; }
T[] _RDA(T = long)(File f, T fix = 0) { auto r = f.readln.chomp.split.to!(T[]); r[] += fix; return r; }
T RD(T = long)() { if (_f.isOpen) return _RD!T(_f); else return _RD!T; }
T[] RDA(T = long)(T fix = 0) { if (_f.isOpen)  return _RDA!T(_f, fix); else return _RDA!T(fix); }

size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;}
size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; }

void chmin(T)(ref T x, T y) { x = min(x, y); } void chmax(T)(ref T x, T y) { x = max(x, y); }
bool inside(T)(T x, T b, T e) { return x >= b && x < e; }
T lcm(T)(T x, T y) { return x * (y / gcd(x, y)); }
double euDist(T)(T[] a, T[] b) { auto c = a.dup; c[] -= b[]; c[] *= c[]; return sqrt(cast(double)c.sum); }
double[] rotate(double[] vec, double rad) { return [cos(rad)*vec[0] - sin(rad)*vec[1], sin(rad)*vec[0] + cos(rad)*vec[1]]; }
double norm(double[] vec) { return sqrt(reduce!((a,b)=>a+b*b)(0.0, vec)); }
double dotProd(double[] a, double[] b) { auto r = a.dup; r[] *= b[]; return r.sum; }

long mod = 10^^9 + 7;
//long mod = 998_244_353;
//long mod = 1_000_003;
void moda(ref long x, long y) { x = (x + y) % mod; }
void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; }
void modm(ref long x, long y) { x = (x * y) % mod; }
void modpow(ref long x, long y) { if (!y) { x = 1; return; } auto t = x; x.modpow(y>>1); x.modm(x); if (y&1) x.modm(t); }
void modd(ref long x, long y) { y.modpow(mod - 2); x.modm(y); }

void main()
{
	auto H = RD;
	auto W = RD;
	bool isRotate = H > W;
	auto a = new long[][](min(H, W), max(H, W));
	foreach (i; 0..H)
	{
		auto S = RD!string;
		foreach (j; 0..W)
		{
			if (isRotate)
				a[j][i] = S[j]-'a';
			else
				a[i][j] = S[j]-'a';
		}
	}
	if (isRotate)
		swap(H, W);

	if (a[0][0] != a[H-1][W-1])
		writeln(0);
	else
	{
		auto dp = new long[][][]((H+W)/2, H, H);
		dp[0][0][0] = 1;
		foreach (i; 0..dp.length-1)
		{
			auto len = min(i+1, H);
			foreach (j; 0..len)
			{
				auto y1 = j;
				auto x1 = i-j;
				foreach (k; 0..len)
				{
					if (dp[i][j][k] == 0) continue;
					auto y2 = H-len+k;
					auto x2 = W-k-1;
					if (a[y1][x1] != a[y2][x2]) continue;
					foreach (dd1, d1; [[0, 1], [1, 0]])
					{
						auto dy1 = y1 + d1[0];
						auto dx1 = x1 + d1[1];
						if (!inside(dy1, 0, H) || !inside(dx1, 0, W)) continue;
						foreach (dd2, d2; [[1, 0], [0, 1]])
						{
							auto dy2 = y2 - d2[0];
							auto dx2 = x2 - d2[1];
							if (!inside(dy2, 0, H) || !inside(dx2, 0, W)) continue;
							if (a[dy1][dx1] == a[dy2][dx2])
							{
								dp[i+1][j+dd1][k+dd2].moda(dp[i][j][k]);
							}
						}
					}
				}
			}
		}
		debug writeln(dp);
		long ans;
		foreach (i; 0..H)
			ans.moda(dp[$-1][i][i]);
		if ((H + W) % 2)
		{
			foreach (i; 0..H-1)
				ans.moda(dp[$-1][i][i+1]);
		}

		writeln(ans);
	}
	
	stdout.flush;
	debug readln;
}