#pragma GCC optimize("O3") #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using ll = long long; using P = pair; using T = tuple; template inline T chmax(T &a, const T b) {return a = (a < b) ? b : a;} template inline T chmin(T &a, const T b) {return a = (a > b) ? b : a;} constexpr int MOD = 1e9 + 7; constexpr int inf = 1e9; constexpr long long INF = 1e18; constexpr double pi = acos(-1); constexpr double EPS = 1e-10; int dx[] = {1, 0, -1, 0}; int dy[] = {0, 1, 0, -1}; ll modpow(ll a, ll b){ if(b == 0) return 1; else if(b % 2 == 0){ ll d = modpow(a, b/2) % MOD; return (d * d) % MOD; } else{ return (a * modpow(a, b-1)) % MOD; } } const int MAX_N = 100010; ll fact[MAX_N], finv[MAX_N]; ll comb(int n, int r){ if(n < r || r < 0) return 0; return fact[n] * finv[n-r] % MOD * finv[r] % MOD; } void calc(int n){ fact[0] = finv[0] = 1; for(int i=1; i<=n; i++){ fact[i] = (fact[i-1] * i) % MOD; finv[i] = modpow(fact[i], MOD-2); } } int main(){ cin.tie(0); ios::sync_with_stdio(false); int n; cin>>n; vector a(n); for(int i=0; i>a[i]; calc(100005); ll ans = 0; for(int i=0; i