#define __USE_MINGW_ANSI_STDIO 0
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
#define int ll
using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define PB push_back

const ll LLINF = (1LL<<60);
const int INF = (1LL<<30);
const int MOD = 1000000007;

template <typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template <typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template <typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }
template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
  out<<'('<<a.first<<','<<a.second<<')';
  return out;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
  out<<'[';
  REP(i, a.size()) {out<<a[i];if(i!=a.size()-1)out<<',';}
  out<<']';
  return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};

string s[505];
int v;
VI g[30];
bool used[30];
vector<int> ans;

void dfs(int u) {
  if(used[u]) return;
  used[u] = true;
  for(auto& i: g[u]) dfs(i);
  // 帰りがけ順で追加
  ans.push_back(u);
}

void tsort() {
  for(int i=0; i<v; ++i) dfs(i);
  reverse(ans.begin(), ans.end());
}

signed main(void)
{
  int h, w;
  cin >> h >> w;
  REP(i, h) cin >> s[i];

  vector<PII> p[30];
  REP(i, h) REP(j, w) {
    if(s[i][j] != '.') p[s[i][j]-'A'].PB({i, j});
  }

  int ret = 0;
  bool update = true;
  while(update) {
    update = false;
    REP(i, 26) {
      if(p[i].size() == 0) continue;
      int l = min(p[i][0].second, p[i][1].second),
          r = max(p[i][0].second, p[i][1].second);
      int u = min(p[i][0].first, p[i][1].first),
          d = max(p[i][0].first, p[i][1].first);
      // cout << char(i+'A') << " " << l << " " << r << " " << u << " " << d << endl;
      if((l+1==r && u==d) || (l==r && u+1==d)) continue;

      if((l == p[i][0].second && u == p[i][0].first) || (l == p[i][1].second && u == p[i][1].first)) {
        // cout << "a" << endl;
        bool flag = true;
        FOR(y, u+1, d) if(s[y][l] != '.') flag = false;
        FOR(x, l, r) if(s[d][x] != '.') flag = false;
        if(flag) {
          s[p[i][0].first][p[i][0].second] = '.';
          s[p[i][1].first][p[i][1].second] = '.';
          p[i].clear();
          ret += 2;
          update = true;
          continue;
        }

        flag = true;
        FOR(y, u, d) if(s[y][r] != '.') flag = false;
        FOR(x, l+1, r) if(s[u][x] != '.') flag = false;
        if(flag) {
          s[p[i][0].first][p[i][0].second] = '.';
          s[p[i][1].first][p[i][1].second] = '.';
          p[i].clear();
          ret += 2;
          update = true;
        }
      } else {
        // cout << "b" << endl;
        bool flag = true;
        FOR(y, u+1, d) if(s[y][l] != '.') flag = false;
        FOR(x, l, r) if(s[u][x] != '.') flag = false;
        if(flag) {
          s[p[i][0].first][p[i][0].second] = '.';
          s[p[i][1].first][p[i][1].second] = '.';
          p[i].clear();
          ret += 2;
          update = true;
          continue;
        }

        flag = true;
        FOR(y, u+1, d+1) if(s[y][r] != '.') flag = false;
        FOR(x, l+1, r) if(s[d][x] != '.') flag = false;
        if(flag) {
          s[p[i][0].first][p[i][0].second] = '.';
          s[p[i][1].first][p[i][1].second] = '.';
          p[i].clear();
          ret += 2;
          update = true;
        }
      }
    }
    // REP(y, h) cout << s[y] << endl;
    // cout << endl;
  }
  cout << ret << endl;

  return 0;
}



Measured memory_bytes: 3336