#include <bits/stdc++.h>
using namespace std;
#pragma comment(linker, "/STACK:1024000000,1024000000")
long long mod = 1e9 + 7;
const long long INF = 1e18;
const double eps = 1e-6;
const int maxn = 5e2 + 5;
template <class T>
inline bool scan_d(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;
}
inline void out(long long x) {
  if (x > 9) out(x / 10);
  putchar(x % 10 + '0');
}
long long dp[2][maxn][maxn];
char G[maxn][maxn];
int main() {
  int n, m;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) scanf("%s", G[i] + 1);
  memset(dp, 0, sizeof(dp));
  dp[0][1][n] = (G[1][1] == G[n][m]);
  int step = n + m - 2;
  int e = 0;
  for (int i = 1; i <= step / 2; i++) {
    e = !e;
    for (int x1 = 1; x1 <= n; x1++) {
      for (int x2 = 1; x2 <= n; x2++) {
        int y1 = i - x1 + 2;
        int y2 = n + m - x2 - i;
        if (y1 < 1 || y2 < 1 || y1 > m || y2 > m) continue;
        dp[e][x1][x2] = 0;
        if (G[x1][y1] == G[x2][y2]) {
          dp[e][x1][x2] = (dp[e][x1][x2] + dp[!e][x1][x2]) % mod;
          dp[e][x1][x2] = (dp[e][x1][x2] + dp[!e][x1][x2 + 1]) % mod;
          dp[e][x1][x2] = (dp[e][x1][x2] + dp[!e][x1 - 1][x2]) % mod;
          dp[e][x1][x2] = (dp[e][x1][x2] + dp[!e][x1 - 1][x2 + 1]) % mod;
        }
      }
    }
  }
  long long ans = 0;
  if ((n + m) & 1) {
    for (int x = 1; x <= n; x++) {
      int y = (step / 2) - x + 2;
      if (y < 1 || y > m) continue;
      ans = (ans + dp[e][x][x] + dp[e][x][x + 1]) % mod;
    }
  } else {
    for (int x = 1; x <= n; x++) {
      int y = (step / 2) - x + 2;
      if (y < 1 || y > m) continue;
      ans = (ans + dp[e][x][x]) % mod;
    }
  }
  printf("%lld\n", ans);
}
