#pragma region おまじないα ver1 .08
//#define _CRT_SECURE_NO_WARNINGS
//#pragma warning(disable : 4996)
// using mint = modint1000000007;
// using mint = modint998244353;
#pragma region 変化しないおまじない
#include "bits/stdc++.h"
#if __has_include("atcoder/all")
#include <atcoder/all>
using namespace atcoder;
#endif
#ifdef ONLINE_JUDGE
#pragma GCC optimize("O3")
#pragma GCC target( \
    "sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#endif
using namespace std;
typedef long long ll;
#define all(x) (x).begin(), (x).end()    // sortなどの引数を省略
#define max3(x, y, z) max(x, max(y, z))  // 3変数min
#define min3(x, y, z) min(x, min(y, z))  // 3変数max
#define chmin(m, v) m = min((m), (v))    //最小値を更新
#define chmax(m, v) m = max((m), (v))    //最大値を更新
#define rep(i, n) repi(i, 0, n)          // 0-N rep
#define reps(i, n) repi(i, 1, n + 1)     // 1-N
#define repi(i, a, b) for (ll i = ll(a); i < ll(b); i++)  // a-b
#define prif(x)    \
  if (x) {         \
    cout << "Yes"; \
  } else {         \
    cout << "No";  \
  }
#define P pair<ll, ll>  // typedefだと予測が効かないっぽい？
#ifdef _MSC_FULL_VER    //手元なら
#define dout cout
#else
#define dout \
  if (false) cout
#endif
double dist(double x1, double y1, double x2, double y2) {
  return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
}
ll idist(ll x1, ll y1, ll x2, ll y2) {
  return (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
}
ll digitsum(ll N) {
  while (N >= 10) {
    int tmp = 0;
    while (N > 0) {
      tmp += (N % 10);
      N /= 10;
    }
    N = tmp;
  }
  return N;
}
struct qwqw {
  qwqw() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(20);
  };
} aaaaaaa;
#pragma endregion
#pragma endregion
signed main() {
  ll N,M;
  cin >> N >> M;
  vector<string> v(N);
  rep(i,N){
    cin >> v[i];
  }
  string b0,b1;
  rep(i,M){
    if(v[0][i]!=v[1][i]){
      b0=v[0].substr(0,i)+v[1][i]+v[0][i]+v[0].substr(i+1,M-1);
      b1=v[1].substr(0,i)+v[0][i]+v[1][i]+v[1].substr(i+1,M-1);
      break;
    }
  }
  ll c=2;
  rep(i,N){
    ll f=0;
    rep(j,M){
      if(v[i][j]!=b0[j+f]){
        f++;
        if(f==2){
          break;
        }
      }
    }
    if(f==2){
      c--;
      break;
    }
  }
  
  rep(i,N){
    ll f=0;
    rep(j,M){
      if(v[i][j-f]!=b1[j]){
        f++;
        if(f==2){
          break;
        }
      }
    }
    
    if(f==2){
      c--;
      break;
    }
  }
  if(b0==b1)c--;
  cout << c << endl;
}