#include <bits/stdc++.h>
using namespace std;
#define PB push_back
#define ZERO (1e-10)
#define INF int(1e9+1)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define DEB printf("DEB!\n");
#define D(X) cout<<"  "<<#X": "<<X<<endl;
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<ii> vii;
#define IN(n) int n;scanf("%d",&n);
#define FOR(i, m, n) for (int i(m); i < n; i++)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define FT(m, n) FOR(k, m, n)
#define aa first
#define bb second
void ga(int N,int *A){F(N)scanf("%d",A+i);}
#define MX (5005)
char s[MX][MX];
int N,M,D[MX][MX];
ll S;
void mrx(){F(N)FF(M/2)swap(s[i][j],s[i][M-j-1]);}
void mry(){F(N/2)FF(M)swap(s[i][j],s[N-i-1][j]);}
ll go(){
    ll S=0;
    F(N)FF(M)S+=D[i][j]=!i||!j||s[i][j]^s[i-1][j]||s[i][j]^s[i][j-1]?1:1+min(D[i][j-1],D[i-1][j]);
    return S;
}
int main(void){
    scanf("%d%d",&N,&M);
    F(N)scanf("%s",s[i]);
    S+=go();
    mrx(),S+=go(),mrx();
    mry(),S+=go(),mry();
    mry(),mrx(),S+=go(),mrx(),mry();
    printf("%lld\n",S-N*M*4);
    return 0;
}