import java.io.PrintWriter
import java.util.*
import kotlin.math.*

fun PrintWriter.solve() {
    val h = nextInt()
    val w = nextInt()
    val s = Array(h) { nextLine().toCharArray() }
    val dp = Array(h + 1) { Array(h + 1) { ModIntArray(h + w) { ModInt(0) } } }
    if (s[0][0] == s[h - 1][w - 1]) {
        dp[0][h - 1][0] = ModInt(1)
    }
    fun inRange(i: Int, j: Int): Boolean {
        return i in 0 until h && j in 0 until w
    }
    for (k in 1 until h + w) {
    for (i in 0 until h) {
        for (j in 0 until h) {
                val l = h + w - 2 - k
                if (inRange(i - 1, k - i)) {
                    if (inRange(j + 1, l - j) && s[i - 1][k - i] == s[j + 1][l - j]) {
                        dp[i][j][k] += dp[i - 1][j + 1][k - 1]
                    }
                    if (inRange(j, l + 1 - j) && s[i - 1][k - i] == s[j][l + 1 - j]) {
                        dp[i][j][k] += dp[i - 1][j][k - 1]
                    }
                }
                if (inRange(i, k - 1 - i)) {
                    if (inRange(j + 1, l - j) && s[i][k - 1 - i] == s[j + 1][l - j]) {
                        dp[i][j][k] += dp[i][j + 1][k - 1]
                    }
                    if (inRange(j, l + 1 - j) && s[i][k - 1 - i] == s[j][l + 1 - j]) {
                        dp[i][j][k] += dp[i][j][k - 1]
                    }
                }
            }
        }
    }
    var ans = ModInt(0)
    val k = (h + w) / 2 - 1
    if ((h + w) % 2 == 0) {
        for (i in 0 until h) {
            ans += dp[i][i][k]
        }
    } else {
        for (i in 0 until h) {
            if (s[i][k - i] == s[i][k + 1 - i]) {
                ans += dp[i][i][k]
            }
            if (i + 1 < h && s[i][k - i] == s[i + 1][k - i]) {
                ans += dp[i][i + 1][k]
            }
        }
    }
    println(ans)
}

// region ModInt
class ModInt(x: Long) {
    companion object {
        //const val MOD = 998244353L
        const val MOD = 1000000007L
    }

    constructor(y: Int) : this(y.toLong())

    val x = (x % MOD + MOD) % MOD

    operator fun plus(other: ModInt): ModInt {
        return ModInt(x + other.x)
    }

    operator fun minus(other: ModInt): ModInt {
        return ModInt(x - other.x)
    }

    operator fun times(other: ModInt): ModInt {
        return ModInt(x * other.x)
    }

    operator fun div(other: ModInt): ModInt {
        return this * other.inv()
    }

    fun pow(exp: Long): ModInt {
        if (exp == 0L) return ModInt(1L)
        var a = pow(exp shr 1)
        a *= a
        if (exp and 1L == 0L) return a
        return this * a
    }

    fun inv(): ModInt {
        return this.pow(MOD - 2)
    }

    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (javaClass != other?.javaClass) return false

        other as ModInt

        if (x != other.x) return false

        return true
    }

    override fun hashCode(): Int {
        return x.hashCode()
    }

    override fun toString(): String {
        return "$x"
    }
}

class ModIntArray(n: Int) {
    private val a = LongArray(n) { 0L }

    constructor(n: Int, init: (Int) -> ModInt) : this(n) {
        for (i in 0 until n) {
            a[i] = init(i).x
        }
    }

    operator fun set(i: Int, x: ModInt) {
        a[i] = x.x
    }

    operator fun get(i: Int): ModInt {
        return ModInt(a[i])
    }

    fun joinToString(s: String): String {
        return a.joinToString(s)
    }
}

fun Long.toModInt(): ModInt {
    return ModInt(this)
}

fun Int.toModInt(): ModInt {
    return ModInt(this)
}

fun binomSimple(n: Long, k: Long): ModInt {
    var numer = ModInt(1)
    var denom = ModInt(1)
    for (i in 0 until k) {
        numer *= ModInt(n - i)
        denom *= ModInt(k - i)
    }
    return numer / denom
}
// endregion

fun main() {
    Thread(null, {
        val writer = PrintWriter(System.out, false)
        writer.solve()
        writer.flush()
    }, "solve", abs(1L.shl(26)))
        .apply { setUncaughtExceptionHandler { _, e -> e.printStackTrace(); kotlin.system.exitProcess(1) } }
        .apply { start() }.join()
}

// region Scanner
private var st = StringTokenizer("")
private val br = System.`in`.bufferedReader()

fun next(): String {
    while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())
    return st.nextToken()
}

fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextLine() = br.readLine()
fun nextDouble() = next().toDouble()
// endregion