#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool RD(T &ret) {
  char c;
  int sgn;
  if (c = getchar(), c == EOF) return 0;
  while (c != '-' && (c < '0' || c > '9')) c = getchar();
  sgn = (c == '-') ? -1 : 1;
  ret = (c == '-') ? 0 : (c - '0');
  while (c = getchar(), c >= '0' && c <= '9') ret = ret * 10 + (c - '0');
  ret *= sgn;
  return 1;
}
template <class T>
inline void PT(T x) {
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  if (x > 9) PT(x / 10);
  putchar(x % 10 + '0');
}
const int N = 500 + 10;
const long long MOD = 1e9 + 7;
char mp[N][N];
long long dp[2][N][N];
int step;
long long DP(int sx, int sy, int gx, int gy) {
  if (mp[sx][sy] != mp[gx][gy]) return 0;
  if (sx > gx || sy > gy) return 0;
  if (sx == gx && sy == gy - 1) return 1;
  if (sy == gy && sx == gx - 1) return 1;
  int k = sx + sy - 1;
  long long ans = 0;
  ans = (ans + dp[(k + 1) & 1][sy][gy]) % MOD;
  ans = (ans + dp[(k + 1) & 1][sy][gy - 1]) % MOD;
  ans = (ans + dp[(k + 1) & 1][sy + 1][gy]) % MOD;
  ans = (ans + dp[(k + 1) & 1][sy + 1][gy - 1]) % MOD;
  return ans;
}
int main() {
  memset(dp, 0, sizeof(dp));
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= int(n); i++) scanf("%s", mp[i] + 1);
  if (n < m) {
    swap(n, m);
    for (int i = 1; i <= int(n); i++)
      for (int j = 1; j <= int(i - 1); j++) swap(mp[i][j], mp[j][i]);
  }
  step = n + m - 1;
  if (step & 1) {
    int sx = step / 2 + 1, sy = 1;
    for (int i = 0; sx - i >= 1 && sy + i <= m; i++)
      dp[sx & 1][sy + i][sy + i] = 1;
  }
  for (int k = step / 2; k >= 1; k--) {
    memset(dp[k & 1], 0, sizeof(dp[k & 1]));
    int sx = k, sy = 1;
    for (int i = 0; sx - i >= 1 && sy + i <= m; i++) {
      int gy = m, gx = n - k + 1;
      for (int j = 0; gx + j <= n && gy - j >= 1; j++)
        dp[k & 1][sy + i][gy - j] = DP(sx - i, sy + i, gx + j, gy - j);
    }
  }
  PT(dp[1][1][m]);
  puts("");
}
