#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define ull unsigned long long

#define REP(i, n) for(int i=0;i<n;i++)

char mat[2000][2000];
int sum[2000][2000];

void clear(int n, int m){
	REP(i,n){
		REP(j,m){
			sum[i][j] = 1;
		}
	}
}

int main() {
	int n, m;
	cin >> n >> m;
	REP(i,n){
		cin >> mat[i];
	}
	
	int s = 0;
	
	clear(n,m);
	
	for(int i=1;i<n;i++){
		for(int j=1;j<m;j++){
			if (mat[i-1][j] == mat[i][j] && mat[i][j-1] == mat[i][j]) {
				int mi = min(sum[i-1][j], sum[i][j-1]);
				sum[i][j] = mi + 1;
				s += sum[i][j]-1;
			}
		}
	}
	
	clear(n,m);
	
	for(int i=1;i<n;i++){
		for(int j=m-2;j>=0;j--){
			if (mat[i-1][j] == mat[i][j] && mat[i][j+1] == mat[i][j]) {
				int mi = min(sum[i-1][j], sum[i][j+1]);
				sum[i][j] = mi + 1;
				s += sum[i][j]-1;
			}
		}
	}
	
	clear(n,m);
	
	for(int i=n-2;i>=0;i--){
		for(int j=1;j<m;j++){
			if (mat[i+1][j] == mat[i][j] && mat[i][j-1] == mat[i][j]) {
				int mi = min(sum[i+1][j], sum[i][j-1]);
				sum[i][j] = mi + 1;
				s += sum[i][j]-1;
			}
		}
	}
	
	clear(n,m);
	
	for(int i=n-2;i>=0;i--){
		for(int j=m-2;j>=0;j--){
			if (mat[i+1][j] == mat[i][j] && mat[i][j+1] == mat[i][j]) {
				int mi = min(sum[i+1][j], sum[i][j+1]);
				sum[i][j] = mi + 1;
				s += sum[i][j]-1;
			}
		}
	}
	
	cout << s << endl;
}