#include <bits/stdc++.h>
using namespace std;
#define LL long long
//#define int LL
#define PB push_back
#define VI vector<int>
#define FOR(i,a,b) for(int i = (a); i <= (b); i++)
#define REP(i,n) FOR(i, 0, (int)n - 1)
#define PII pair<int,int>
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define st first
#define nd second

template<class C> void mini(C & a4, C b4){a4 = min(a4, b4);}
template<class C> void maxi(C & a4, C b4){a4 = max(a4, b4);}

template<class TH> void _dbg(const char * sdbg, TH h){
	cerr<<sdbg<<'='<<h<<endl;
}
template<class TH, class... TA> void _dbg(const char * sdbg, TH h, TA... a){
	while(*sdbg!=',')
		cerr<<*sdbg++;
	cerr<<'='<<h<<",";
	_dbg(sdbg + 1, a...);
}
template<class T> ostream & operator<<(ostream & os, vector<T> V){
	os<<"[";for(auto vv: V) os <<vv<<","; return os <<"[";
}
template<class L, class R> ostream & operator<<(ostream & os , pair<L,R> P){
	return os << "(" << P.st <<","<<P.nd<<")";
}
#ifdef LOCAL
#define debug(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (__VA_ARGS__)
#define cerr if(0) cout
#endif 

const int N = 1005;

char board[N][N];
int n, m;

int dpLeftUp[N][N], dpRightUp[N][N], dpLeftDown[N][N], dpRightDown[N][N];

int32_t main(){
	//ios_base::sync_with_stdio(0);
	//cin.tie(0);
	
	scanf("%d %d", &n, &m);
	for (int i = 1; i <= n; i++) {
		scanf("%s", &board[i][1]);
	}
	
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {\
			if (board[i - 1][j] != board[i][j] || board[i][j - 1] != board[i][j]) {
				dpLeftUp[i][j] = 1;
				continue;
			}
			dpLeftUp[i][j] = min(dpLeftUp[i - 1][j], dpLeftUp[i][j - 1]) + 1;
		}
	}
	
	for (int i = 1; i <= n; i++) {
		for (int j = m; j >= 1; j--) {
			if (board[i - 1][j] != board[i][j] || board[i][j + 1] != board[i][j]) {
				dpRightUp[i][j] = 1;
				continue;
			}
			dpRightUp[i][j] = min(dpRightUp[i - 1][j], dpRightUp[i][j + 1]) + 1;
		}
	}
	
	for (int i = n; i >= 1; i--) {
		for (int j = 1; j <= m; j++) {
			if (board[i + 1][j] != board[i][j] || board[i][j - 1] != board[i][j]) {
				dpLeftDown[i][j] = 1;
				continue;
			}
			dpLeftDown[i][j] = min(dpLeftDown[i + 1][j], dpLeftDown[i][j - 1]) + 1;
		}
	}
	
	for (int i = n; i >= 1; i--) {
		for (int j = m; j >= 1; j--) {
			if (board[i + 1][j] != board[i][j] || board[i][j + 1] != board[i][j]) {
				dpRightDown[i][j] = 1;
				continue;
			}
			dpRightDown[i][j] = min(dpRightDown[i + 1][j], dpRightDown[i][j + 1]) + 1;
		}
	}
	
	long long ans = 0;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			//debug(i, j, dpLeftUp[i][j], dpLeftDown[i][j], dpRightUp[i][j], dpRightDown[i][j]);
			ans += dpLeftUp[i][j] + dpLeftDown[i][j] + dpRightUp[i][j] + dpRightDown[i][j] - 4;
		}
	}
	
	printf("%lld\n", ans);
	
	return 0;
}