#include<bits/stdc++.h>
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) (int) (x).size()
#define pb push_back
#define fi first
#define se second

using namespace std;

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef long double LD;

const int maxn = 1e3 + 7;

int dp[maxn][maxn], prawo[maxn][maxn], dol[maxn][maxn], tab[maxn][maxn];

LL res = 0;
int n, m;

void rob()
{
	for(int i = n - 1;i >= 0;i--)
		for(int j = m - 1;j >= 0;j--)
		{
			if(tab[i + 1][j] == tab[i][j])
				dol[i][j] = dol[i + 1][j] + 1;
			else
				dol[i][j] = 1;
			if(tab[i][j + 1] == tab[i][j])
				prawo[i][j] = prawo[i][j + 1] + 1;
			else
				prawo[i][j] = 1;
			dp[i][j] = 0;
			if(tab[i + 1][j + 1] == tab[i][j])
				dp[i][j] = dp[i + 1][j + 1] + 2;
			else
				dp[i][j] = 1;
			dp[i][j] = min(dp[i][j], min(prawo[i][j] - 1, dol[i][j] - 1));
			res += (LL)dp[i][j];
			//cerr<<i<<" "<<j<<" "<<dp[i][j]<<endl;
		}
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	for(int i = 0;i< n;i++)
		for(int j = 0;j < m;j++)
		{
			char a;
			cin>>a;
			tab[i][j] = (int)a;
		}
	rob();
	for(int i = 0;i < n / 2;i++)
		for(int j = 0; j< m;j++)
			swap(tab[i][j], tab[n - 1 - i][j]);
	rob();
	for(int j = 0;j < m / 2;j++)
		for(int i = 0;i < n;i++)
			swap(tab[i][j], tab[i][m - 1 - j]);
	rob();
	for(int i = 0;i < n / 2;i++)
		for(int j = 0; j< m;j++)
			swap(tab[i][j], tab[n - 1 - i][j]);
	rob();
	cout<<res<<"\n";
	return 0;
}