#[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();
    }

    if s[0][0] != s[h - 1][w - 1] {
        println!("0");
        return;
    }

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

    let v = (h + w - 2) / 2;

    let m = 1_000_000_007;

    for i in 0..h {
        for j in 0..w {
            if i + j >= v {
                continue;
            }

            for ni in (0..h).rev() {
                // i + j = (h-1-ni) + (w-1-nj)
                let nj = w + h - (i + j) - 2 - ni;
                if nj >= w || i > ni || j > nj {
                    continue;
                }
                if i + 1 < ni && s[i + 1][j] == s[ni - 1][nj] {
                    dp[i + 1][j][ni - 1] += dp[i][j][ni];
                    dp[i + 1][j][ni - 1] %= m;
                }
                if i < ni && j < nj && s[i + 1][j] == s[ni][nj - 1] {
                    dp[i + 1][j][ni] += dp[i][j][ni];
                    dp[i + 1][j][ni] %= m;
                }
                if i < ni && j < nj && s[i][j + 1] == s[ni - 1][nj] {
                    dp[i][j + 1][ni - 1] += dp[i][j][ni];
                    dp[i][j + 1][ni - 1] %= m;
                }
                if j + 1 < nj && s[i][j + 1] == s[ni][nj - 1] {
                    dp[i][j + 1][ni] += dp[i][j][ni];
                    dp[i][j + 1][ni] %= m;
                }
            }
        }
    }

    let mut ans = 0;
    for i in 0..h {
        for j in 0..w {
            for k in 0..h {
                if i + j == v {
                    ans += dp[i][j][k];
                    ans %= m;
                }
            }
        }
    }
    println!("{}", ans);
}

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