const int MAXN = 5e4;

int main() {
    fast
    // file_in

    int n, m;
    cin >> n >> m;
    vector<vector<bitset<MAXN>>> mk(m, vector<bitset<MAXN>>(27));
    ll ans = 0;
    bitset<MAXN> res, cur;
    res.set();
    for (int g = 0; g < n; ++g) {
        string s;
        cin >> s;
        for (int i = 0; i < m; ++i) {
            if (s[i] == '?') {
                for (int j = 0; j < 27; ++j) {
                    cur |= mk[i][j];
                }
                mk[i][26][g] = 1;
            } else {
                cur |= mk[i][s[i] - 'a'];
                cur |= mk[i][26];
                mk[i][s[i] - 'a'][g] = 1;
            }
            res &= cur;
            cur.reset();
        }
        ans += res.count();
        res.set(); cur.reset();
    }
    cout << ans << '\n';
    return 0;
}