#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

int n, m;
vector<vector<char> > input;

long long ans(vector<vector<ll> > &v){
  ll res = 0;
  /*for(int i = 0; i < n; i++){
    for(int j = 0; j < m; j++){
        cout << v[i][j] << " ";
    } cout << endl;
  }*/

  vector<vector<ll> > prev(n, vector<ll> (m, 1));
  for(int j = m-1; j >= 0; j--){
    for(int i = n-2; i >= 0; i--){
      if(input[i][j] == input[i+1][j]) prev[i][j] = min(prev[i+1][j]+1, v[i][j]);
      if(prev[i][j] > 1) res += prev[i][j] - 1;
    }
  }
 // cout << res << endl;
  return res;
}

int main(){
  scanf("%d%d ", &n, &m );
  //cout << n << " " << m << endl;
  char c;
  input.resize(n);
  for(int i = 0; i < n; i++){
    for(int j = 0; j < m; j++){
      scanf("%c ", &c);
      input[i].push_back(c);
    }
  }

   /* for(int i = 0; i < n; i++){
    for(int j = 0; j < m; j++){
        cout << input[i][j] << " ";
    } cout << endl;
  }*/

  vector<vector<ll> > v;
  v.resize(0);
  v.resize(n, vector<ll> (m, 1));
  for(int i = 0; i < n; i++){
    for(int j = m-2; j >= 0; j--){
      if(input[i][j] == input[i][j+1]) v[i][j] += v[i][j+1];
    }
  }
  ll res = ans(v);


  for(int i = 0; i < n; i++){
    for(int j = 0; j < m/2; j++)
        swap(input[i][j], input[i][m-1-j]);
   }
    v.resize(0);
    v.resize(n, vector<ll> (m, 1));
  for(int i = 0; i < n; i++){
    for(int j = m-2; j >= 0; j--){
      if(input[i][j] == input[i][j+1]) v[i][j] += v[i][j+1];
    }
  }
   res += ans(v);


   for(int i = 0; i < n/2; i++){
    for(int j = 0; j < m; j++){
        swap(input[i][j], input[n-1-i][j]);
    }
   }
     v.resize(0);
  v.resize(n, vector<ll> (m, 1));
  for(int i = 0; i < n; i++){
    for(int j = m-2; j >= 0; j--){
      if(input[i][j] == input[i][j+1]) v[i][j] += v[i][j+1];
    }
  }
   res += ans(v);

  for(int i = 0; i < n; i++){
    for(int j = 0; j < m/2; j++)
        swap(input[i][j], input[i][m-1-j]);
   }
     v.resize(0);
  v.resize(n, vector<ll> (m, 1));
  for(int i = 0; i < n; i++){
    for(int j = m-2; j >= 0; j--){
      if(input[i][j] == input[i][j+1]) v[i][j] += v[i][j+1];
    }
  }
   res += ans(v);

   cout << res << endl;

  return 0;
}