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


#define int long long

char M[4][1000][1001];
int dp[1000][1001];
int result = 0;

void f(int k, int n, int m)
{
	for(int i=0; i<max(n, m); i++)
		{dp[i][0] = 0; dp[0][i]=0;}

	
	for(int i=1; i<n; i++)
	for(int j=1; j<m; j++)
	{
		dp[i][j] = 0;
		if(M[k][i][j] == M[k][i-1][j] && M[k][i][j] == M[k][i][j-1])
			dp[i][j] = min(dp[i-1][j], dp[i][j-1]) + 1;
		result += dp[i][j];
	}
}

int32_t main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n,m;
	cin>>n>>m;
	for(int i=0;i<n;++i) cin>>M[0][i];
	
	for(int i=1;i<4;++i) {
		int a = (i%2 ? m : n);
		int b = n+m-a;
		for(int k=0;k<a;k++){
			for(int l=0;l<b;l++)
				M[i][k][l] = M[i-1][l][k];
			reverse(M[i][k], M[i][k] + b);
		}
	}
	
	f(0, n, m);
	f(1, m, n);
	f(2, n, m);
	f(3, m, n);
	
	cout << result << endl;
}