#include <bits/stdc++.h>
using namespace std;
string tab[1005];
int prawo[1005][1005];
int lewo[1005][1005];
int mgl[1005][1005];
int mdl[1005][1005];
int mgp[1005][1005];
int mdp[1005][1005];
int32_t main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n, m;
	cin >> n >> m;
	for (int i=1; i<=n; i++)
	{
		cin >> tab[i];
		tab[i] = "#" + tab[i];
	}
	for (int i=1; i<=n; i++)
	{
		prawo[i][m]=1;
		for (int j=m-1; j>0; j--)
		{
			if (tab[i][j]==tab[i][j+1])
				prawo[i][j]=prawo[i][j+1]+1;
			else
				prawo[i][j]=1;
		}
		lewo[i][1]=1;
		for (int j=2; j<=m; j++)
		{
			if (tab[i][j]==tab[i][j-1])
				lewo[i][j]=lewo[i][j-1]+1;
			else
				lewo[i][j]=1;
		}
	}
	long long wyn=0;
	for (int i=n; i>0; i--)
	{
		for (int j=1; j<=m; j++)
		{
			if (i!=n && tab[i+1][j]==tab[i][j])
			{
				mdp[i][j]=min(mdp[i+1][j]+1, prawo[i][j]);
				mdl[i][j]=min(mdl[i+1][j]+1, lewo[i][j]);
			}
			else
			{
				mdp[i][j]=1;
				mdl[i][j]=1;
			}
		}
	}
	for (int i=1; i<=n; i++)
	{
		for (int j=1; j<=m; j++)
		{
			if (i!=1 && tab[i][j]==tab[i-1][j])
			{
				mgp[i][j]=min(mgp[i-1][j]+1, prawo[i][j]);
				mgl[i][j]=min(mgl[i-1][j]+1, lewo[i][j]);
			}
			else
			{
				mgp[i][j]=1;
				mgl[i][j]=1;
			}
			wyn+=mdp[i][j]+mdl[i][j]+mgp[i][j]+mgl[i][j]-4;
		}
	}
	cout << wyn << "\n";
	return 0;
}