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

const MOD: usize = 1e9 as usize + 7;
const SDX: [isize; 2] = [-1, 0];
const SDY: [isize; 2] = [0, -1];
const EDX: [usize; 2] = [1, 0];
const EDY: [usize; 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 temp = String::new();
            std::io::stdin().read_line(&mut temp).ok();
            let temp = temp.trim();
            temp.chars().collect::<Vec<_>>()
        })
        .collect::<Vec<_>>();

    let mut dp = HashMap::new();
    let middle = (h+w-2) / 2;
    if (h+w) % 2 == 0 {
        for i in 0..h.min(w) {
            if h > w {
                dp.insert((middle-i, i, middle-i, i), 1);
            } else {
                dp.insert((i, middle-i, i, middle-i), 1);
            }
        }
    } else {
        for i in 0..h.min(w) {
            if h > w {
                if grid[middle-i][i] == grid[middle-i+1][i] {
                    *dp.entry((middle-i, i, middle-i+1, i)).or_insert(0usize) += 1;
                }
                if i + 1 < w && grid[middle-i][i] == grid[middle-i][i+1] {
                    *dp.entry((middle-i, i, middle-i, i+1)).or_insert(0usize) += 1;
                }
            } else {
                if grid[i][middle-i] == grid[i][middle-i+1] {
                    *dp.entry((i, middle-i, i, middle-i+1)).or_insert(0usize) += 1;
                }
                if i + 1 < h && grid[i][middle-i] == grid[i+1][middle-i] {
                    *dp.entry((i, middle-i, i+1, middle-i)).or_insert(0usize) += 1;
                }
            }
        }
    }
    for _ in 0..(h+w-2)/2 {
        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 + SDX[sdir];
                let nsy = sy as isize + SDY[sdir];
                if nsx >= 0 && nsy >= 0 {
                    let nsx = nsx as usize;
                    let nsy = nsy as usize;
                    for gdir in 0..2 {
                        let ngx = gx + EDX[gdir];
                        let ngy = gy + EDY[gdir];
                        if ngx < h && ngy < w {
                            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));
}