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

typedef long long LL;

const int N = 1e3 + 7;

int n, m, T[4][N][N];
char S[N][N];

int main()
{
	scanf("%d %d", &n, &m);
	for(int i = 1; i <= n; i++)
	{
		scanf(" %s", S[i] + 1);
	}
	LL ans = 0;
	
	for(int i = n; i; i--)
	{
		for(int j = m; j; j--)
		{
			T[0][i][j] = 1;
			if(i < n && j < m)
			{
				if(S[i][j] == S[i + 1][j] && S[i][j] == S[i][j + 1])
				{
					T[0][i][j] += min(T[0][i + 1][j], T[0][i][j + 1]);
				}
			}
			ans += T[0][i][j] - 1;
		}
	}
	
	for(int i = n; i; i--)
	{
		for(int j = 1; j <= m; j++)
		{
			T[1][i][j] = 1;
			if(i < n && 1 < j)
			{
				if(S[i][j] == S[i + 1][j] && S[i][j] == S[i][j - 1])
				{
					T[1][i][j] += min(T[1][i + 1][j], T[1][i][j - 1]);
				}
			}
			ans += T[1][i][j] - 1;
		}
	}
	
	for(int i = 1; i <= n; i++)
	{
		for(int j = m; j; j--)
		{
			T[2][i][j] = 1;
			if(1 < i && j < m)
			{
				if(S[i][j] == S[i - 1][j] && S[i][j] == S[i][j + 1])
				{
					T[2][i][j] += min(T[2][i - 1][j], T[2][i][j + 1]);
				}
			}
			ans += T[2][i][j] - 1;
		}
	}
	
	for(int i = 1; i <= n; i++)
	{
		for(int j = 1; j <= m; j++)
		{
			T[3][i][j] = 1;
			if(1 < i && 1 < j)
			{
				if(S[i][j] == S[i - 1][j] && S[i][j] == S[i][j - 1])
				{
					T[3][i][j] += min(T[3][i - 1][j], T[3][i][j - 1]);
				}
			}
			ans += T[3][i][j] - 1;
		}
	}
	
	printf("%lld\n", ans);
	
	return 0;
}