use std::collections::{HashMap, HashSet};


const MOD: usize = 1e9 as usize + 7;
const SDX: [isize; 2] = [1, 0];
const SDY: [isize; 2] = [0, 1];
const EDX: [isize; 2] = [-1, 0];
const EDY: [isize; 2] = [0, -1];

fn main() {
    let mut hw = String::new();
    std::io::stdin().read_line(&mut hw).ok();
    let hw: Vec<usize> = hw.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let h = hw[0];
    let w = hw[1];
    let grid = (0..h).map(|_| {
            let mut s = String::new();
            std::io::stdin().read_line(&mut s).ok();
            let s = s.trim();
            s.chars().map(|c| c as usize - 'a' as usize).collect::<Vec<usize>>()
        })
        .collect::<Vec<Vec<usize>>>();

    if grid[0][0] != grid[h-1][w-1] {
        println!("0");
        return;
    }
    let mut dp = HashMap::new();
    if (h+w) % 2 == 0 {
        for i in 0..h.min(w) {
            let x = if h > w { (h+w)/2-1-i } else { i };
            let y = if w >= h { (h+w)/2-1-i } else { i };
            dp.insert((x, y, x, y), 1);
        }
    } else {
        for i in 0..h.min(w) {
            let x = if h > w { (h+w)/2-1-i } else { i };
            let y = if w >= h { (h+w)/2-1-i } else { i };
            for dir in 0..2 {
                let nx = x as isize + SDX[dir];
                let ny = y as isize + SDY[dir];
                if nx >= 0 && ny >= 0 && nx < h as isize && ny < w as isize {
                    let nx = nx as usize;
                    let ny = ny as usize;
                    if grid[x][y] == grid[nx][ny] {
                        *dp.entry((x, y, nx, ny)).or_insert(0usize) += 1;
                    }
                }
            }
        }
    }
    for _ in 0..(h+w)/2-1 {
        let mut next_dp = HashMap::new();
        for (&(sx, sy, gx, gy), &cnt) in dp.iter() {
            for sdir in 0..2 {
                let nsx = sx as isize + EDX[sdir];
                let nsy = sy as isize + EDY[sdir];
                if !(nsx >= 0 && nsy >= 0 && nsx < h as isize && nsy < w as isize) { continue; }
                let nsx = nsx as usize;
                let nsy = nsy as usize;
                for gdir in 0..2 {
                    let ngx = gx as isize + SDX[gdir];
                    let ngy = gy as isize + SDY[gdir];
                    if !(ngx >= 0 && ngy >= 0 && ngx < h as isize && ngy < w as isize) { continue; }
                    let ngx = ngx as usize;
                    let ngy = ngy as usize;
                    if grid[nsx][nsy] == grid[ngx][ngy] {
                        *next_dp.entry((nsx, nsy, ngx, ngy)).or_insert(0usize) += cnt;
                        *next_dp.entry((nsx, nsy, ngx, ngy)).or_insert(0usize) %= MOD;
                    }
                }
            }
        }
        dp = next_dp;
    }
    println!("{}", dp.get(&(0, 0, h-1, w-1)).unwrap_or(&0usize));
}