#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}());
const ll mod=998244353;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head
const int N=2010;
int n,m,nxt[N][N],alive[N];
char s[N][N];
bitset<N> sm[N];
VI ex[N];
ll ans=0;
int main() {
    scanf("%d%d",&n,&m);
    for (int i=0;i<n;i++) scanf("%s",s[i]);
    rep(j,0,m) {
        nxt[n-1][j]=n-1;
        per(i,0,n-1) if (s[i][j]==s[i+1][j]) nxt[i][j]=nxt[i+1][j]; else nxt[i][j]=i;
    }
    rep(i,0,n) rep(k,0,m) sm[i][k]=s[i][k]!=s[i][k-1];
    rep(i,0,n) {
        rep(j,i,n) ex[j].clear();
        rep(j,0,m) ex[nxt[i][j]].pb(j);
        rep(j,0,m) alive[j]=1;
        rep(j,i,n) {
            if (j!=i) {
                bitset<N> bs=sm[i]|sm[j];
                int c=alive[0],d=0;
                for (int k=1;k<m;k++) {
                    if (bs[k]) c=0;
                    if (alive[k]) d+=c,c+=1;
                }
                ans+=d;
            }
            for (auto x:ex[j]) alive[x]=0;

        }
    }
    printf("%lld\n",ans);
}