#include<bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define ll long long
using namespace std;

ll n,ppow[200000],m;
const ll p=31;
const ll mod = 1e9 + 9;

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);

    freopen("rolling_table.in","r",stdin);
    freopen("rolling_table.out","w",stdout);

    cin >> n >> m;

    ll lista[n+10][m+10];
    ll dp[6][n+10][m+10];
    for(ll i=1;i<=n;i++){
        string s;
        cin >> s;
        for(ll j=0;j<m;j++){
            lista[i][j+1]=s[j]-'a'+1;
        }
    }

    ppow[0]=1;
    for(ll i=1;i<=n*m+10;i++){
        ppow[i]=ppow[i-1]*p;
        ppow[i]%=mod;
    }
    for(ll k=0;k<=5;k++){
        for(ll i=0;i<=n+5;i++){
            for(ll j=0;j<=m+5;j++){
                dp[k][i][j]=0;
            }
        }
    }
    ///gorelevo
    for(ll i=1;i<=n;i++){
        ll temphash=0;
        for(ll j=1;j<=m;j++){
            temphash+=lista[i][j]*ppow[j-1];
            temphash%=mod;
            dp[0][i][j]=dp[0][i-1][j]+ppow[(i-1)*j]*temphash;
            dp[0][i][j]%=mod;
            //cout << dp[0][i][j] << ' ';
        }
        //cout << endl;
    }
    ///dolelevo
    for(ll i=n;i>=1;i--){
        ll temphash=0;
        for(ll j=1;j<=m;j++){
            temphash+=lista[i][j]*ppow[j-1];
            temphash%=mod;
            dp[2][i][j]=dp[2][i+1][j]*ppow[j]+temphash;
            dp[2][i][j]%=mod;
            //cout << dp[2][i][j] << ' ';
        }
        //cout << endl;
    }
    ///goredesno
    for(ll i=1;i<=n;i++){
        ll temphash=0;
        for(ll j=m;j>=1;j--){
            temphash=temphash*ppow[1]+lista[i][j];
            temphash%=mod;
            dp[1][i][j]=dp[1][i-1][j]+ppow[(i-1)*(m-j+1)]*temphash;
            dp[1][i][j]%=mod;
            //cout << dp[1][i][j] << ' ';
        }
        //cout << endl;
    }
    ///doledesno
    for(ll i=n;i>=1;i--){
        ll temphash=0;
        for(ll j=m;j>=1;j--){
            temphash=temphash*ppow[1]+lista[i][j];
            temphash%=mod;
            dp[3][i][j]=dp[3][i+1][j]*ppow[m-j+1]+temphash;
            dp[3][i][j]%=mod;
            //cout << dp[3][i][j] << ' ';
        }
        //cout << endl;
    }
    ll res=0;
    for(ll i=1;i<=n;i++){
        for(ll j=1;j<=m;j++){

            if(dp[0][n-i][m-j] == dp[3][i+1][j+1] && dp[1][i][j+1]==dp[2][n-i+1][m-j] && dp[0][i][j]==dp[3][n-i+1][m-j+1] && dp[2][i+1][j]==dp[1][n-i][m-j+1])
                res++;
        }
    }
    cout << res;
    return 0;
}