#include <bits/stdc++.h>
using namespace std;
#define _ <<" "<<
#define sz(x) ((int) (x).size())
typedef pair<int, int> pii;
typedef long long ll;
const int maxn = 5e5 + 5;
const int charid[] = {'W','A','L','D','O'};

int id[1000];

int n, m;
vector<vector<char>> A;
vector<vector<int>> sum[6];

int getsum(int k,int a,int b,int c,int d) {
    return sum[k][c][d] - sum[k][c][b-1] - sum[k][a-1][d] + sum[k][a-1][b-1]; 
}

bool getall(int a,int b,int c,int d) {
    int ret = 1;
    for (int i = 1;i <= 5; ++i) ret &= getsum(i,a,b,c,d) > 0;
    return ret;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    
    cin >> n >> m;
    if (n > m) {
        swap(n, m);
        A = vector<vector<char>>(n+1,vector<char>(m+1));
        for (int i = 1;i <= m; ++i) {
            for (int j = 1;j <= n; ++j) {
                cin >> A[j][i];
            }
        }
    } else {
        A = vector<vector<char>>(n+1,vector<char>(m+1));
        for (int i = 1;i <= n; ++i) {
            for (int j = 1;j <= m; ++j) {
                cin >> A[i][j];
            }
        }
    }
    for (int i = 0;i < 5; ++i) {
        id[charid[i]] = i+1;
        sum[i+1] = vector<vector<int>>(n+1,vector<int>(m+1));
    }
    for (int i = 1;i <= n; ++i) {
        for (int j = 1;j <= m; ++j) if (id[A[i][j]]) {
            sum[id[A[i][j]]][i][j] = 1;
        }
    }

    for (int k = 1;k <= 5; ++k) {
        for (int i = 1;i <= n; ++i) {
            for (int j = 1;j <= m; ++j) {
                sum[k][i][j] += sum[k][i-1][j];
            }
        }
    }
    for (int k = 1;k <= 5; ++k) {
        for (int i = 1;i <= n; ++i) {
            for (int j = 1;j <= m; ++j)  {
                sum[k][i][j] += sum[k][i][j-1];
            }
        }
    }
    int ans = INT_MAX;
    for (int i = 1;i <= n; ++i) {
        for (int j = 1;j <= m; ++j) {
            for (int d = 1;d <= n; ++d) if (getall(d,1,i,j)) {
                int L = 1, R = j, M;
                while (L < R) {
                    M = (L+R)/2+1;
                    if (getall(d,M,i,j)) L = M;
                    else R = M-1;
                }
                ans = min(ans, (i-d+1) * (j-L+1));
            }
        }
    }
    if (ans == INT_MAX) {
        cout << "impossible\n";
        return 0;
    }
    // cout << "hhh" << endl;
    cout << ans << '\n';
    return 0;
}