/// tban lecodes el bosta2
#pragma GCC optimize("O3")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;


#define pb push_back
#define F first
#define S second
#define f(i, a, b)  for(int i = a; i < b; i++)
#define all(a)  a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define sz(x) (int)(x).size()
#define mp(x,y) make_pair(x,y)
#define popCnt(x) (__builtin_popcountll(x))
#define int ll

using ll = long long;
using ii = pair<int, int>;
using ull = unsigned long long;
const int N = 2e5+5, LG = 18, MOD = 1e9+7;
const long double PI = acos(-1);
const long double EPS = 1e-7;

const string TARGET = "WALDO";

vector<vector<char> > a;
vector<vector<int> > pref[5];
int n, m;

vector<vector<int> > build(char c) {
    vector<vector<int> > pref(n + 1, vector<int>(m + 1, 0));
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            pref[i][j] = (a[i][j] == c) + pref[i - 1][j] + pref[i][j - 1] - pref[i - 1][j - 1];
        }
    }
    return pref;
}

int get(int r, int r2, int c, int c2, int idx) {
    return pref[idx][r2][c2] - pref[idx][r - 1][c2] - pref[idx][r2][c - 1] + pref[idx][r - 1][c - 1];
}

bool check(int r, int r2, int c, int c2) {
    for(int i = 0; i < 5; i++) {
        if(get(r, r2, c, c2, i) == 0) return 0;
    }
    return 1;
}

void doWork() {
    cin >> n >> m;
    a = vector<vector<char>> (min(n + 1, m + 1), vector<char>(max(n + 1,m + 1)));

    f(i,1,n+1)
    f(j,1,m+1) {
        if(n<m) cin >> a[i][j];
        else cin >> a[j][i];
    }

    if(n > m) swap(n, m);
    for(int i = 0; i < 5; i++) pref[i] = build(TARGET[i]);

    ll ans = n * m + 1;
    for(int r1 = 1; r1 <= n; r1++)
    for(int r2 = 1; r2 <= n; r2++)
    for(int c1 = 1, c2 = 1; c1 <= m; c1++) {
        while(c2 <= m && !check(r1, r2, c1, c2))c2++;
        if(c2 <= m && check(r1,r2,c1,c2)) {
            ans = min(ans,(r2-r1+1)*(c2-c1+1));
        }
    }

    if(ans > n * m) cout << "impossible\n";
    else
        cout << ans << '\n';

}
int32_t main() {
#ifdef ONLINE_JUDGE
    ios_base::sync_with_stdio(0);
    cin.tie(0);
#endif // ONLINE_JUDGE

    int t = 1;
//    cin >> t;
    while (t--) {
        doWork();
    }
    return 0;
}