#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n, m;
const int maxn = 1100;
char A[maxn][maxn];
int B[maxn][maxn];
int C[maxn][maxn];
ll jebaj()
{
	for(int i = 0; i < maxn; ++i)
		for(int j = 0; j < maxn; ++j)
			B[i][j] = C[i][j] = 0;
	ll res = 0;
	for(int i = n-1; i >= 0; --i)
		for(int j = m - 1; j >= 0; --j)
		{
			if(A[i+1][j] == A[i][j])
			{
				B[i][j] = B[i+1][j] + 1;
			}
			else
				B[i][j] = 1;
			
			if(A[i][j+1] == A[i][j])
				C[i][j] = min(C[i][j+1] + 1, B[i][j]);
			else
				C[i][j] = 1;
			
			if(C[i][j] > 1)
				res += C[i][j] - 1;
			
		}
	return res;
}
int main()
{
	scanf("%d%d", &n, &m);
	for(int i = 0; i < n; ++i)
		scanf("%s", A[i]);
	
	ll res = 0;
	res += jebaj();
	for(int i = 0; i < n / 2; ++i)
		for(int j = 0; j < m; ++j)
			swap(A[i][j], A[n-i-1][j]);
	res += jebaj();
	for(int i = 0; i < n; ++i)
		for(int j = 0; j < m / 2; ++j)
			swap(A[i][j], A[i][m-1-j]);
	res += jebaj();
	for(int i = 0; i < n / 2; ++i)
		for(int j = 0; j < m; ++j)
			swap(A[i][j], A[n-i-1][j]);
	res += jebaj();
	
	printf("%lld\n", res);
}