#include <bits/stdc++.h>

using namespace std;

//#define int long long

#define IOS ios::sync_with_stdio(false); cin.tie(0);

//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
//typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
std::mt19937 rnd(std::chrono::steady_clock::now().time_since_epoch().count());

const int INF = 1e9 + 7;
const double EPS = 1e-10;
const int MOD = 1e9 + 7;
const int MAXN = 2e3 + 100;

int n, m;
char a[MAXN][MAXN];
int dist[MAXN][MAXN];

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

inline void solve() {
    cin >> n >> m;
    pair<int, int> start;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            cin >> a[i][j];
            dist[i][j] = -1;
            if (a[i][j] == 'X') {
                start = {i, j};
            }
        }
    }

    int mx = 0, cnt = 0;
    bool odd = false, even = false;
    queue<pair<int, int>> q;
    q.push(start);
    dist[start.first][start.second] = 0;
    while (!q.empty()) {
        auto [i, j] = q.front();
        q.pop();
        if (a[i][j] == 'I') {
            odd |= (dist[i][j] % 2 == 0);
            even |= (dist[i][j] % 2 == 1);
            mx = max(mx, dist[i][j]);
            ++cnt;
            continue;
        }
        for (int k = 0; k < 4; ++k) {
            int x = i + dx[k], y = j + dy[k];
            if (x >= 0 && x < n && y >= 0 && y < m) {
                if (a[x][y] != 'B' && dist[x][y] == -1) {
                    q.emplace(x, y);
                    dist[x][y] = dist[i][j] + 1;
                }
            }
        }
    }
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            if (a[i][j] == 'I' && dist[i][j] == -1) {
                cout << "-1\n";
                return;
            }
        }
    }
    if (odd && even) {
        cout << "-1\n";
    } else {
        cout << cnt * mx << '\n';
    }
}


int32_t main() {
    IOS;
    clock_t tStart = clock();

    int tt = 1;
//    cin >> tt;
    while (tt --> 0) {
        solve();
    }
//    cerr << "Runtime is:" << (long double) (clock() - tStart) / CLOCKS_PER_SEC << '\n';
    return 0;
}
/*
1.  数组开够了没
2.  文件名写对了没，文件夹建了吗
3.  内存会不会MLE
4.  多测清空？
5.  调试删干净了没
6.  取模有没有溢出
7.  快速幂底数要取模，幂对 mod-1 取模
8.  前向星和欧拉序要开2倍数组
9.  比较函数如果值相同的话有没有第二优先级
10. 线段树 4 倍空间，线段树合并和可持久化线段树 32 倍空间
11. 看清楚 log 的底数是啥，log后面的数是啥
12. long long 只有正负 2^63-1
*/