[CSES] Grid Paths

void solve()
{
    ll n;
    cin >> n;

    vector<string> s(n);
    rep(i, n) cin >> s[i];

    if (s[0][0] == '*')
    {
        cout << 0 << "\n";
        return;
    }

    vvll dp(n, vll(n, 0));
    dp[0][0] = 1;

    FOR(i, 1, n - 1)
    if (s[0][i] != '*')
        dp[0][i] = dp[0][i - 1];

    FOR(i, 1, n - 1)
    if (s[i][0] != '*')
        dp[i][0] = dp[i - 1][0];

    FOR(i, 1, n - 1)
    {
        FOR(j, 1, n - 1)
        {
            if (s[i][j] != '*')
            {
                if (i - 1 >= 0)
                    dp[i][j] += dp[i - 1][j];
                dp[i][j] %= mod;
                if (j - 1 >= 0)
                    dp[i][j] += dp[i][j - 1];
                dp[i][j] %= mod;
            }
        }
    }

    cout << dp[n - 1][n - 1] << "\n";
}