// #include #include #define FOR(i, a, n) for(ll i = (ll)a; i < (ll)n; i++) #define FORR(i, n) for(ll i = (ll)n - 1LL; i >= 0LL; i--) #define rep(i, n) FOR(i, 0, n) #define ALL(x) begin(x), end(x) using namespace std; using ll = long long; constexpr ll Mod = 998244353; constexpr ll mod = 1e9 + 7; constexpr ll inf = 1LL << 60; const double PI = acos(-1); template inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); } template inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); } /*-------------------------------------------*/ int main() { cin.tie(nullptr); ios::sync_with_stdio(false); int n; cin >> n; vector a(n); ll x = 1; rep(i, n) { cin >> a[i]; if(a[i] == 1) x *= 1; else if(a[i] == 2) x *= 4; else if(a[i] == 3) x *= 729; } if(*min_element(ALL(a)) == 0) { cout << -1 << endl; return 0; } if(*max_element(ALL(a)) >= 4) { cout << mod << endl; return 0; } cout << mod % x << endl; return 0; }