#[allow(clippy::many_single_char_names)]
fn main() {
    let s = getline();
    let a = s.split(' ').collect::<Vec<_>>();
    let h = a[0].parse::<usize>().unwrap();
    let w = a[1].parse::<usize>().unwrap();
    let mut s = vec![vec!['a'; w]; h];

    for i in 0..h {
        s[i] = getline().chars().collect();
    }

    let mut dp = vec![vec![vec![vec![0; w]; h]; w]; h];
    dp[0][0][h - 1][w - 1] = 1;

    let m = 1_000_000_007;

    for i in 0..h {
        for j in 0..w {
            for ni in (0..h).rev() {
                for nj in (0..w).rev() {
                    if ni < i || nj < j {
                        continue;
                    }
                    if i + 1 < ni && s[i + 1][j] == s[ni - 1][nj] {
                        dp[i + 1][j][ni - 1][nj] += dp[i][j][ni][nj];
                        dp[i + 1][j][ni - 1][nj] %= m;
                    }
                    if i < ni && j < nj && s[i + 1][j] == s[ni][nj - 1] {
                        dp[i + 1][j][ni][nj - 1] += dp[i][j][ni][nj];
                        dp[i + 1][j][ni][nj - 1] %= m;
                    }
                    if i < ni && j < nj && s[i][j + 1] == s[ni - 1][nj] {
                        dp[i][j + 1][ni - 1][nj] += dp[i][j][ni][nj];
                        dp[i][j + 1][ni - 1][nj] %= m;
                    }
                    if j + 1 < nj && s[i][j + 1] == s[ni][nj - 1] {
                        dp[i][j + 1][ni][nj - 1] += dp[i][j][ni][nj];
                        dp[i][j + 1][ni][nj - 1] %= m;
                    }
                }
            }
        }
    }
    let mut ans = 0;
    for i in 0..h {
        for j in 0..w {
            ans += dp[i][j][i][j];
            ans %= m;
        }
    }
    println!("{}", ans);
}

fn getline() -> String {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    buf.trim().to_string()
}