#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a; i<b; i++)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define debug printf
#define cerr if(0)cout

typedef long long ll;
typedef pair<int, int> pii;

const int duzo = 1007;
char t[duzo][duzo];
int dp1[duzo][duzo], dp2[duzo][duzo], dp3[duzo][duzo], dp4[duzo][duzo];

int main()
{
	ios_base::sync_with_stdio(0);
//	cin.tie(0);
	int n, m;
	cin >> n >> m;
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cin >> t[i][j];
		}
	}
	for(int i = 2; i <= n; ++i) {
		for(int j = 2; j <= m; ++j) {
			if(t[i][j] == t[i - 1][j] && t[i][j] == t[i][j - 1])
				dp1[i][j] = min(dp1[i][j - 1], dp1[i - 1][j]) + 1;
		}
	}
	for(int i = 2; i <= n; ++i) {
		for(int j = m - 1; j >= 1; --j) {
			if(t[i][j] == t[i - 1][j] && t[i][j] == t[i][j + 1])
				dp2[i][j] = min(dp2[i][j + 1], dp2[i - 1][j]) + 1;
		}
	}
	for(int i = n - 1; i >= 1; --i) {
		for(int j = 2; j <= m; ++j) {
			if(t[i][j] == t[i + 1][j] && t[i][j] == t[i][j - 1])
				dp3[i][j] = min(dp3[i][j - 1], dp3[i + 1][j]) + 1;
		}
	}
	for(int i = n - 1; i >= 1; --i) {
		for(int j = m - 1; j >= 1; --j) {
			if(t[i][j] == t[i + 1][j] && t[i][j] == t[i][j + 1])
				dp4[i][j] = min(dp4[i][j + 1], dp4[i + 1][j]) + 1;
		}
	}
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cerr << dp1[i][j] << " ";
		}
		cerr << "\n";
	}
	cerr << "\n";
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cerr << dp2[i][j] << " ";
		}
		cerr << "\n";
	}
	cerr << "\n";
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cerr << dp3[i][j] << " ";
		}
		cerr << "\n";
	}
	cerr << "\n";
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			cerr << dp4[i][j] << " ";
		}
		cerr << "\n";
	}
	cerr << "\n";
	
	ll sum = 0ll;
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			sum += (ll)dp1[i][j];
			sum += (ll)dp2[i][j];
			sum += (ll)dp3[i][j];
			sum += (ll)dp4[i][j];
		}
	}
	cout << sum;
	return 0;
}