#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define PA pair<ll,ll>
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
#define COU(A,x) (UB(A,x)-LB(A,x))
//#include<boost/multiprecision/cpp_int.hpp>
//namespace mp=boost::multiprecision;
//using Bint=mp::cpp_int;
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}
template<class T>void print(vector<T>A){REP(i,A.size()){if(i)cout<<" ";cout<<A[i];}cout<<endl;}
ld dist(ld x1,ld y1,ld x2,ld y2){return sqrtl((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}
//using mint=modint1000000007;
using mint=modint998244353;
//const ll mod=1000000007;
const ll mod=998244353;
int main(){
  ll N,M;cin>>N>>M;
  vector<string>S(N);
  REP(i,N)cin>>S[i];
  sort(ALL(S));
  if(S[0]==S.back()){cout<<26*(M+1)<<endl;return 0;}
  ll ans=0;
  ll t=0;
  while(S[0][t]==S.back()[t])t++;
  string T=S[0].substr(0,t+1)+S.back().substr(t,M-t);
  set<string>K;
  vector<string>Mae(M+1),Usiro(M+1);
  REP(i,M)Mae[i+1]=Mae[i]+T[i];
  RREP(i,M)Usiro[i]=T[i+1]+Usiro[i+1];
  REP(i,M+1)K.insert(Mae[i]+Usiro[i]);
  bool ok=1;
  REP(i,N)if(!K.count(S[i]))ok=0;
  ans+=ok;
  T=S.back().substr(0,t+1)+S[0].substr(t,M-t);
  K.clear();
  REP(i,M)Mae[i+1]=Mae[i]+T[i];
  RREP(i,M)Usiro[i]=T[i+1]+Usiro[i+1];
  REP(i,M+1)K.insert(Mae[i]+Usiro[i]);
  ok=1;
  REP(i,N)if(!K.count(S[i]))ok=0;
  ans+=ok;
  cout<<ans<<endl;
  return 0;
}