#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;

struct Pt{
    ll x,y;
};

#define MX 1008
char a[MX][MX];
ll c[MX][MX];

int main(){
    ll N,M;cin>>N>>M;
    memset(a, ' ', sizeof a);
    for(int j=1; j<=N; ++j){
        string s;cin>>s;
        for(int k=1; k<=M; ++k){
            a[j][k]=s[k-1];
        }
    }
    ll res=0;
    for(ll dx:{-1,1}){
        for(ll dy:{-1,1}){
            memset(c, 0ll, sizeof c);
            ll x=(dx==1)?1:M;
            for(int cx=1; cx<=M; ++cx){
                ll y=(dy==1)?1:N;
                for(int cy=1; cy<=N; ++cy){
                    //cerr<<x<<' '<<y<<endl;
                    ll r=N+M;
                    r=min(r,(a[y][x]==a[y][x-dx])?c[x-dx][y]+1:0);
                    r=min(r,(a[y][x]==a[y-dy][x])?c[x][y-dy]+1:0);
                    c[x][y]=r;
                    res+=r;
                    y+=dy;
                }
                x+=dx;
            }
            //for(int j=0; j<N+2; ++j){
            //    for(int k=0; k<M+2; ++k){
            //        cerr<<c[k][j];
            //    }
            //    cerr<<endl;
            //}
            //cerr<<endl;
        }
    }
    cout<<res<<endl;
    //for(int x:{-1,1}){
    //    for(int y:{-1,1}){
    //        vector<vector<ll>> c(N+2,vector<ll>(M+2,0));
    //        Pt s={x==1?1:N,y==1?1:M};
    //    }
    //}
    return 0;
}