#include <algorithm>
#include <vector>
#include <string>
#include <iostream>

using namespace std;

typedef long long ll;
typedef long double ld;
#define rep(i, a, n) for (int i = (a); i < (n); i++)
#define per(i, a, n) for (int i = (n) - 1; i >= (a); i--)

ll work(vector<string> &A) {
	int R = A.size(), C = A[0].size();
//	rep(r, 0, R)
//		cout << A[r] << endl;

	vector<vector<ll>> p(R);
	rep(i, 0, R) p[i].resize(C);
	rep(r, 0, R) rep(c, 0, C)
		p[r][c] = (c && A[r][c] == A[r][c - 1]) ? p[r][c -1] : c;
	
	vector<vector<ll>> d(R);
	rep(i, 0, R) d[i].resize(C, 1LL);
	rep(r, 0, R) rep(c, 0, C)
		if (r && c && A[r][c] == A[r - 1][c - 1]) {
//			cout << "a" << r << " " << c << "\n";
			d[r][c] = min(c - p[r][c] + 1, d[r - 1][c - 1] + 1);
		}
	
//	rep(r, 0, R) {
//		rep(c, 0, C)
//			cout << d[r][c] << " ";
//		cout << endl;
//	}
//
//	cout << endl;
//	rep(r, 0, R) {
//		rep(c, 0, C)
//			cout << p[r][c] << " ";
//		cout << endl;
//	}

	ll s = 0;
	rep(r, 0, R) rep(c, 0, C)
		s += d[r][c] - 1;
	
//	cout << s << endl;
	return s;
}

int main(void)
{
	ios_base::sync_with_stdio(false);
	int R, C;
	cin >> R >> C;
	vector<string> A(R);
	getline(cin, A[0]);
	rep(r, 0, R) {
		getline(cin, A[r]);
	}

	ll sum = 0;
	sum += work(A);
	rep(r, 0, R)
		reverse(A[r].begin(), A[r].end());
	sum += work(A);
	reverse(A.begin(), A.end());
	sum += work(A);
	rep(r, 0, R)
		reverse(A[r].begin(), A[r].end());
	sum += work(A);
	cout << sum << endl;
}