#include <bits/stdc++.h>
#define pb push_back
#define FOR(i, a, b) for(int i = a; i < b; i++)
//#define FOR(i, a) FOR(i, 0, a)
#define st first
#define nd second
//#pragma GCC optimize ("Ofast")
//#pragma GCC target("sse, sse2, sse3, sse4, popcnt, abm, mmx, avx, time=native")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;

const int MAX = 1000;
char A[MAX][MAX];
int B[MAX][MAX];
int C[MAX][MAX];
int R[MAX][MAX];


int main() {
	ios_base::sync_with_stdio(0);
	int n, m;
	cin>>n>>m;
	
	for(int i=0; i<n; i++) {
		for(int j=0; j<m; j++) {
			cin>>A[i][j];
		}
	}
	
	ll res = 0;
	
	// ###
	// 1
	// ###
	for(int i=0; i<n; i++) {
		B[i][m-1] = 1;
		for(int j=m-2; j>=0; j--) {
			B[i][j] = 1;
			if(A[i][j] == A[i][j+1])
				B[i][j] += B[i][j+1];
		}
	}
	
	for(int j=0; j<m; j++) {
		C[n-1][j] = 1;
		for(int i=n-2; i>=0; i--) {
			C[i][j] = 1;
			if(A[i][j] == A[i+1][j])
				C[i][j] += C[i+1][j];
		}
	}
	
	
	int j;
	for(int i=n-1; i>=0; i--) {
		j = m-1;
		char c = A[i][m-1];
		int r = 1;
		R[i][m-1] = 0;
		int r2;
		
		
		for(int k=0; i-k >= 0; k++) {
			
			if(A[i-k][j-k] == c) {
				r2 = min(B[i-k][j-k], C[i-k][j-k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
				//cout<<" "<<i-k<<" "<<j-k<<" "<<c<<" "<<r<<" "<<r2<<endl;
			} else {
				c = A[i-k][j-k];
				r = min(B[i-k][j-k], C[i-k][j-k]);
				r = min(2, r);
				//cout<<" "<<i-k<<" "<<j-k<<" "<<c<<" "<<r<<" "<<endl;
			}
			R[i-k][j-k] = r;
			res += (r-1);
		}
	}
	int i;
	for( j = m-2; j>=0; j--) {
		i = n-1;
		char c = A[i][j];
		int r = 1;
		R[i][j] = 0;
		int r2;
		
		for(int k=0; i-k >= 0 && j-k >= 0; k++) {
			
			if(A[i-k][j-k] == c) {
				r2 = min(B[i-k][j-k], C[i-k][j-k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
				//cout<<" "<<i-k<<" "<<j-k<<" "<<c<<" "<<r<<" "<<r2<<endl;
			} else {
				c = A[i-k][j-k];
				r = min(B[i-k][j-k], C[i-k][j-k]);
				r = min(2, r);
				//cout<<" "<<i-k<<" "<<j-k<<" "<<c<<" "<<r<<" "<<endl;
			}
			R[i-k][j-k] = r;
			res += (r-1);
		}
	}
	
	// ###
	// 2
	// ###
	for(i=0; i<n; i++) {
		B[i][0] = 1;
		for(j=1; j<m; j++) {
			B[i][j] = 1;
			if(A[i][j] == A[i][j-1])
				B[i][j] += B[i][j-1];
		}
	}
	
	for(j=0; j<m; j++) {
		C[0][j] = 1;
		for(i=1; i<n; i++) {
			C[i][j] = 1;
			if(A[i][j] == A[i-1][j])
				C[i][j] += C[i-1][j];
		}
	}
	
	
	j = 0;
	for(i=0; i<n; i++) {
		j = 0;
		char c = A[i][j];
		int r = 1;
		R[i][j] = 0;
		int r2;
		
		for(int k=0; i+k < n && j+k < m; k++) {
			
			if(A[i+k][j+k] == c) {
				r2 = min(B[i+k][j+k], C[i+k][j+k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
			} else {
				c = A[i+k][j+k];
				r = min(B[i+k][j+k], C[i+k][j+k]);
				r = min(2, r);
			}
			R[i+k][j+k] = r;
			res += (r-1);
		}
	}

	for(j = 1; j<m; j++) {
		i = 0;
		char c = A[i][j];
		int r = 1;
		R[i][j] = 0;
		int r2;
		
		for(int k=0; i-k >= 0 && j-k >= 0; k++) {
			if(A[i+k][j+k] == c) {
				r2 = min(B[i+k][j+k], C[i+k][j+k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
			} else {
				c = A[i+k][j+k];
				r = min(B[i+k][j+k], C[i+k][j+k]);
				r = min(2, r);
			}
			R[i+k][j+k] = r;
			res += (r-1);
		}
	}
	
	// ###
	// 3
	// ###
	for(i=0; i<n; i++) {
		B[i][0] = 1;
		for(j=1; j<m; j++) {
			B[i][j] = 1;
			if(A[i][j] == A[i][j-1])
				B[i][j] += B[i][j-1];
		}
	}
	
	for(j=0; j<m; j++) {
		C[n-1][j] = 1;
		for(i=n-2; i>=0; i--) {
			C[i][j] = 1;
			if(A[i][j] == A[i+1][j])
				C[i][j] += C[i+1][j];
		}
	}
	
	for(i=0; i<n; i++) {
		j = 0;
		char c = A[i][j];
		int r = 1;
		R[i][j] = 0;
		int r2;
		
		for(int k=0; i-k < n && j+k < m; k++) {
			
			if(A[i-k][j+k] == c) {
				r2 = min(B[i-k][j+k], C[i-k][j+k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
			} else {
				c = A[i-k][j+k];
				r = min(B[i-k][j+k], C[i-k][j+k]);
				r = min(2, r);
			}
			R[i-k][j+k] = r;
			res += (r-1);
		}
	}

	for(j = 1; j<m; j++) {
		i = n-1;
		char c = A[i][j];
		int r = 1;
		R[i][j] = 0;
		int r2;
		
		for(int k=0; i-k < n && j+k < m; k++) {
		
			if(A[i-k][j+k] == c) {
				r2 = min(B[i-k][j+k], C[i-k][j+k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
			} else {
				c = A[i-k][j+k];
				r = min(B[i-k][j+k], C[i-k][j+k]);
				r = min(2, r);
			}
			R[i-k][j+k] = r;
			res += (r-1);
		}
	}
	
	// ###
	// 4
	// ###
	for(i=0; i<n; i++) {
		B[i][m-1] = 1;
		for(j=m-2; j>=0; j--) {
			B[i][j] = 1;
			if(A[i][j] == A[i][j+1])
				B[i][j] += B[i][j+1];
		}
	}
	
	for(j=0; j<m; j++) {
		C[0][j] = 1;
		for(i=1; i<n; i++) {
			C[i][j] = 1;
			if(A[i][j] == A[i-1][j])
				C[i][j] += C[i-1][j];
		}
	}
	
	for(i=0; i<n; i++) {
		j = m-1;
		char c = A[i][j];
		int r = 1;
		R[i][j] = 0;
		int r2;
		
		for(int k=0; i+k < n && j-k < m; k++) {
			
			if(A[i+k][j-k] == c) {
				r2 = min(B[i+k][j-k], C[i+k][j-k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
			} else {
				c = A[i+k][j-k];
				r = min(B[i+k][j-k], C[i+k][j-k]);
				r = min(2, r);
			}
			R[i+k][j-k] = r;
			res += (r-1);
		}
	}

	for(j = m-2; j>=0; j--) {
		i = 0;
		char c = A[i][j];
		int r = 1;
		R[i][j] = 0;
		int r2;
		
		for(int k=0; i+k < n && j-k < m; k++) {
			
			if(A[i+k][j-k] == c) {
				r2 = min(B[i+k][j-k], C[i+k][j-k]);
				if(r2 >= r + 2)
					r += 2;
				else r = min(2, r2);
			} else {
				c = A[i+k][j-k];
				r = min(B[i+k][j-k], C[i+k][j-k]);
				r = min(2, r);
			}
			R[i+k][j-k] = r;
			res += (r-1);
		}
	}
	
	cout<<res<<endl;
	
 	return 0;
}