#include <iostream>
#define FOR(i, b, e) for(int i = b; i <= e; i++)
#define FORD(i, b, e) for(int i = b; i >= e; i--)

using namespace std;

typedef long long LL;

const int maxn = 1042;
int n, m;
char a[maxn][maxn];
int dp[maxn][maxn];
LL ans;

int main()
{
	ios_base::sync_with_stdio(false);
	
	cin >> n >> m;
	
	FOR(i, 1, n)
		FOR(j, 1, m)
			cin >> a[i][j];
			
	
	FORD(i, n-1, 1)
		FORD(j, m-1, 1)
		{
			if(a[i][j] == a[i + 1][j] && a[i][j] == a[i][j+1])
			{
				dp[i][j] = min(dp[i + 1][j], dp[i][j + 1]) + 1;
				ans += dp[i][j];
			}
		}
	
	FOR(i, 1, n)	
		FOR(j, 1, m)
			dp[i][j] = 0;
			
	FOR(i, 2, n)
		FOR(j, 2, m)
		{
			if(a[i][j] == a[i - 1][j] && a[i][j] == a[i][j-1])
			{
				dp[i][j] = min(dp[i - 1][j], dp[i][j - 1]) + 1;
				ans += dp[i][j];
			}
		}
		
	FOR(i, 1, n)	
		FOR(j, 1, m)
			dp[i][j] = 0;
			
	FORD(i, n - 1, 1)
		FOR(j, 2, m)
		{
			if(a[i][j] == a[i + 1][j] && a[i][j] == a[i][j - 1])
			{
				dp[i][j] = min(dp[i + 1][j], dp[i][j - 1]) + 1;
				ans += dp[i][j];
			}
		}
		
	FOR(i, 1, n)	
		FOR(j, 1, m)
			dp[i][j] = 0;
			
	FOR(i, 2, n)
		FORD(j, m - 1, 1)
			if(a[i][j] == a[i - 1][j] && a[i][j] == a[i][j + 1])
			{
				dp[i][j] = min(dp[i - 1][j], dp[i][j + 1]) + 1;
				ans += dp[i][j];
			}
		
	cout << ans << '\n';
	
	
}