#include <bits/stdc++.h>
using namespace std;

using ll=long long;
using ld=long double;
using vi=vector<int>;
using ii=pair<int, int>;

#define FOR(i,a,b) for(int i=a; i < b; i++)
#define F(n) FOR(i, 0, n)
#define FF(n) FOR(j, 0, n)
#define aa first
#define bb second
#define PB push_back

int main() {
	ios::sync_with_stdio(0);
	int N, M; cin >> N >> M;
	vector<vector<char>> T(N, vector<char>(M));
	for (auto && row : T) for (auto && v : row) cin >> v;

	vector<vector<int>> L(N, vector<int>(M));
	vector<vector<int>> R(N, vector<int>(M));
	vector<vector<int>> U(N, vector<int>(M));
	vector<vector<int>> D(N, vector<int>(M));

	for (int i = 0; i < N; i++)
		for (int j = M - 2; j >= 0; j--)
			R[i][j] = ((T[i][j] == T[i][j+1]) ? R[i][j+1] + 1 : 0);

	for (int i = 0; i < N; i++)
		for (int j = 1; j < M; j++)
			L[i][j] = ((T[i][j] == T[i][j-1]) ? L[i][j-1] + 1 : 0);

	for (int i = 1; i < N; i++)
		for (int j = 0; j < M; j++)
			U[i][j] = ((T[i][j] == T[i-1][j]) ? U[i-1][j] + 1 : 0);

	for (int i = N - 2; i >= 0; i--)
		for (int j = 0; j < M; j++)
			D[i][j] = ((T[i][j] == T[i+1][j]) ? D[i+1][j] + 1 : 0);
	
	vector<vector<int>> RD(N, vector<int>(M));
	vector<vector<int>> RU(N, vector<int>(M));
	vector<vector<int>> LD(N, vector<int>(M));
	vector<vector<int>> LU(N, vector<int>(M));

	for (int i = 0; i < N; i++)
		for (int j = 0; j < M; j++) {
			RU[i][j] = min(R[i][j], U[i][j]);
			RD[i][j] = min(R[i][j], D[i][j]);
			LU[i][j] = min(L[i][j], U[i][j]);
			LD[i][j] = min(L[i][j], D[i][j]);
		}

	vector<vector<int>> TRD(N, vector<int>(M));
	vector<vector<int>> TRU(N, vector<int>(M));
	vector<vector<int>> TLD(N, vector<int>(M));
	vector<vector<int>> TLU(N, vector<int>(M));

	int i, j;
	vector<pair<int, int>> starts;
	for (int j = 0; j < M; j++)
		starts.emplace_back(N - 1, j);
	for (int i = 0; i < N; i++)
		starts.emplace_back(i, M - 1);
	starts.pop_back();
	for (auto && s : starts) {
		tie(i, j) = s;
		i--; j--;
		for (; i >= 0 && j >= 0; i--, j--) {
			if (T[i][j] == T[i+1][j+1])
				TRD[i][j] = min(RD[i][j], TRD[i+1][j+1]+2);
			else TRD[i][j] = (RD[i][j] != 0);
		}
	}
	starts.clear();
	for (int j = 0; j < M; j++)
		starts.emplace_back(0, j);
	starts.pop_back();
	for (int i = 0; i < N; i++)
		starts.emplace_back(i, M - 1);
	for (auto && s : starts) {
		tie(i, j) = s;
		i++; j--;
		for (; i < N && j >= 0; i++, j--) {
			if (T[i][j] == T[i-1][j+1])
				TRU[i][j] = min(RU[i][j], TRU[i-1][j+1]+2);
			else TRU[i][j] = (RU[i][j] != 0);
		}
	}
	starts.clear();
	for (int j = 0; j < M; j++)
		starts.emplace_back(N - 1, j);
	for (int i = 0; i < N; i++)
		starts.emplace_back(i, 0);
	starts.pop_back();
	for (auto && s : starts) {
		tie(i, j) = s;
		i--; j++;
		for (;i >= 0 && j < M; i--, j++) {
			if (T[i][j] == T[i+1][j-1])
				TLD[i][j] = min(LD[i][j], TLD[i+1][j-1]+2);
			else TLD[i][j] = (LD[i][j] != 0);
		}
	}
	starts.clear();
	for (int j = 0; j < M; j++)
		starts.emplace_back(0, j);
	for (int i = 1; i < N; i++)
		starts.emplace_back(i, 0);
	for (auto && s : starts) {
		tie(i, j) = s;
		i++; j++;
		for (; i < N && j < M; i++, j++) {
			if (T[i][j] == T[i-1][j-1])
				TLU[i][j] = min(LU[i][j], TLU[i-1][j-1]+2);
			else TLU[i][j] = (LU[i][j] != 0);
		}
	}
	/*
	for (int i = 0; i < N; i++)
		for (int j = 0; j < M; j++) {
			cout << "TRD: " << i << ' ' << j << '\n';
			cout << TRD[i][j] << '\n';
			cout << "TRU: " << i << ' ' << j << '\n';
			cout << TRU[i][j] << '\n';
			cout << "TLD: " << i << ' ' << j << '\n';
			cout << TLD[i][j] << '\n';
			cout << "TLU: " << i << ' ' << j << '\n';
			cout << TLU[i][j] << '\n';
		}
	*/
	int sum = 0;
	for (int i = 0; i < N; i++)
		for (int j = 0; j < M; j++)
			sum += TRD[i][j] + TRU[i][j] + TLD[i][j] + TLU[i][j];

	cout << sum << '\n';
		
	
  return 0;
}