#include <bits/stdc++.h>
using namespace std;
int tt, tc;

#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

// inline char cn() {
// 	static char buf[1000010], *p1 = buf,*p2 = buf;
// 	return p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, 1000000, stdin), p1 == p2) ? EOF : *p1++;
// }

// void read(int& x) {
// 	x = 0; char ch = cn();
// 	while (ch < '0' || ch > '9') ch = cn();
// 	while (ch >= '0' && ch <= '9') x = x * 10 + (ch - '0'), ch = cn();
// }

// void read(char& x) {
// 	char ch = cn();
// 	while (ch < 'A' || ch > 'Z') ch = cn();
// 	x = ch;
// }

template<class T>
struct RMQ {
	vector<vector<T>> jmp;
	RMQ() {}
	RMQ(const vector<T>& V) : jmp(1, V) {
		for (int pw = 1, k = 1; pw * 2 <= sz(V); pw *= 2, ++k) {
			jmp.emplace_back(sz(V) - pw * 2 + 1);
			rep(j,0,sz(jmp[k]))
				jmp[k][j] = min(jmp[k - 1][j], jmp[k - 1][j + pw]);
		}
	}
	T query(int a, int b) {
		assert(a < b); // or return inf if a == b
		int dep = 31 - __builtin_clz(b - a);
		return min(jmp[dep][a], jmp[dep][b - (1 << dep)]);
	}
};

char imp[] = { 'W', 'A', 'L', 'D', 'O' };

int solve(const vector<vector<char>>& v, int h, int w) {
	vector<vector<vector<int>>> nxt(5, vector<vector<int>>(h, vector<int>(w, 1e7)));
	for (int k = 0; k < 5; k++)
		for (int j = 0; j < w; j++)
			for (int i = h - 2; i >= 0; --i) nxt[k][i][j] = (v[i + 1][j] == imp[k] ? i + 1 : nxt[k][i + 1][j]);
	
	int ans = 1e9;
	int sq = sqrt(h * w) + 5;
	for (int row = 0; row < h; row++) {
		vector<RMQ<int>> rmq(5);
		for (int k = 0; k < 5; k++) {
			vector<int> seq(w);
			for (int col = 0; col < w; col++) seq[col] = (v[row][col] == imp[k] ? 1 : nxt[k][row][col] - row + 1);
			rmq[k] = RMQ(seq);
		}

		for (int len = 1; len <= min(w, sq); len++) {
			for (int col = 0; col + len - 1 < w; col++) {
				int mx = -1e9;
				for (int k = 0; k < 5; k++) mx = max(mx, rmq[k].query(col, col + len));
				// if (len == 5 && row == 0) cout << mx << endl;
				ans = min(ans, mx * len);
			}
		}
	}

	return ans;
}


void solve() {
	int h, w;
	cin >> h >> w;
	vector<vector<char>> v(h, vector<char>(w));
	for (auto& u : v) for (auto& p : u) cin >> p;

	int ans = solve(v, h, w);

	vector<vector<char>> vv(w, vector<char>(h));
	for (int j = 0; j < w; j++)
		for (int i = 0; i < h; i++)
			vv[j][i] = v[i][j];
	
	ans = min(ans, solve(vv, w, h));

	cout << (ans <= h * w ? to_string(ans) : "impossible") << "\n";
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    tt = 1, tc = 1; // cin >> tt;
    while (tt--) solve(), tc++;
}