#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("unroll-loops")
//#pragma warning(disable : 4996)


#ifdef _MSC_VER
#include <intrin.h>

#define __builtin_popcount __popcnt
#define __builtin_popcountll __popcnt64
#endif

#include <limits.h>
#include <math.h>
#include <time.h>

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <complex>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#include<atcoder/all>


using namespace std;
using namespace atcoder;


#define REP(i, n) for (int i = 0; i < (n); ++i)
#define REPR(i, n) for (int i = n - 1; i >= 0; --i)
#define FOR(i, m, n) for (int i = m; i < n; ++i)
#define FORR(i, m, n) for (int i = m - 1; i >= n; --i)
#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define REVERSE(v, n) reverse(v, v + n);
#define VREVERSE(v) reverse(v.begin(), v.end())
using ll = long long;
#define print(x) cout << (x) << endl
#define pe(x) cout << (x) << " "
#define DEBUG(x) cout << #x << ": " << x << endl
#define lb(v, n) lower_bound(v.begin(), v.end(), (n))
#define ub(v, n) upper_bound(v.begin(), v.end(), (n))
//using ll = __int128_t;
#define int ll
//#define double long double
#define all(x) (x).begin(), (x).end()
#define print_space(v) REP(i, v.size()) cout << v[i] << " \n"[i==(int)v.size()-1]
template <typename T1, typename T2> inline void chmin(T1& a, T2 b) { if (a > b) a = b; }
template <typename T1, typename T2> inline void chmax(T1& a, T2 b) { if (a < b) a = b; }
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
std::random_device rd;
std::mt19937 mt(rd());
constexpr ll MOD = 1e9 + 7;
constexpr int MAX = 300010;
const double pi = acos(-1);
constexpr double EPS = 1e-8;

constexpr ll LINF = 1e18 + 1;
constexpr int INF = 1e9 + 1;
void Yes(bool cond) { cout << (cond ? "Yes" : "No") << '\n'; }
void YES(bool cond) { cout << (cond ? "YES" : "NO") << '\n'; }


int N, M;
char A[55][55];
int dp[55][55];
int toid(int x, int y) {
	return x * M + y;
}
set<pii>bfs(int sx,int sy){
	set<pii>res;
	queue<pii>que;
	que.push({ sx,sy });
	res.insert({ sx,sy });
	while (!que.empty()) {
		pii p = que.front(); que.pop();
		int x = p.first, y = p.second;
		int nx = x + 1, ny = y + 1;
		if (nx < N&&A[nx][y] != '#' && !res.count({nx,y})) {
			res.insert({ nx,y });
			que.push({ nx,y });
		}
		pii nxt = { x,ny };
		if (ny < M&&A[x][ny] != '#' && !res.count(nxt)) {
			res.insert(nxt);
			que.push(nxt);
		}
	}
	return res;
}


void solve() {
	cin >> N >> M;
	int K = 0;
	vector<pii>v;
	REP(i, N) {
		REP(j, M) {
			cin >> A[i][j];
			if (A[i][j] == 'o') {
				K++;
				dp[i][j] = 1;
				v.push_back({ i,j });
			}
		}
	}
	mcf_graph<int, int> G(N*M+K+2);
	int s = N * M + K, t = N * M + K+1;

	int sum = N * M;
	REP(i, K) {
		pii p = v[i];
		int x = p.first, y = p.second;
		G.add_edge(s, sum + i, 1, 0);
		G.add_edge(sum + i, t, 1, INF);
		set<pii>res = bfs(p.first, p.second);
		//DEBUG(x);
		//DEBUG(y);
		for (auto p : res) {
			int nx = p.first, ny = p.second;
			//DEBUG(nx); DEBUG(ny);
			int c = nx - x + ny - y;
			G.add_edge(sum + i, toid(nx, ny), 1, 0);
		}
	}
	REP(i, N)REP(j, M) {
		G.add_edge(toid(i, j), t, 1, INF - (i + j));
	}
	ll need = 0;
	REP(i, K) {
		pii p = v[i];
		int x = p.first, y = p.second;
		need += x + y;
	}
	pii ret = G.flow(s, t);
	ll fl = ret.first;
	//DEBUG(fl);
	//DEBUG(K);
	ll ans = INF * K - ret.second - need;
	print(ans);
}




signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	//int q;
	//cin >> q;
	//while (q--)
	solve();

}


Measured memory_bytes: 8760