#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={1,0,-1,0,1,1,-1,-1};
const ll dx[8]={0,1,0,-1,1,-1,1,-1};
template <typename T> inline bool chmax(T &a, T b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
  return ((a > b) ? (a = b, true) : (false));
}

int main(){
  ll n,m;cin >> n >> m;
  vector<string> v(n);rep(i,n)cin >> v[i];
  ll f=-1,t=-1;
  rep(i,m){
    f=i;
    if(v[0][i]!=v[1][i])break;
  }
  per(i,m){
    t=i+1;
    if(v[0][i]!=v[1][i])break;
  }
  //cout << f <<" " << t << endl;
  string s;
  string ss;
  rep(i,t)s+=v[0][i];s+=v[1][t-1];
  repl(i,t,m)s+=v[1][i];
  rep(i,t)ss+=v[1][i];ss+=v[0][t-1];
  repl(i,t,m)ss+=v[0][i];
  //cout << s << endl;
  //cout << ss << endl;
  ll ans=0;
  {
     bool ok=true;
    rep(i,n){
      ll k=0;
      rep(j,m+1){
        if(s[j]==v[i][k])k++;
      }
      if(k!=m)ok=false;
    }
    if(ok)ans++;
  }
  {
    bool ok=true;
    s=ss;
    rep(i,n){
      ll k=0;
      rep(j,m+1){
        if(s[j]==v[i][k])k++;
      }
      if(k!=m)ok=false;
    }
    if(ok)ans++;
  }
  cout << ans << endl;
}