#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define rep(x, s, t) for(llint x = (s); (x) <= (t); (x)++) #define per(x, s, t) for(llint x = (s); (x) >= (t); (x)--) #define reps(x, s) for(llint x = 0; (x) < (llint)(s).size(); (x)++) #define chmin(x, y) (x) = min((x), (y)) #define chmax(x, y) (x) = max((x), (y)) #define sz(x) ((ll)(x).size()) #define ceil(x, y) (((x)+(y)-1) / (y)) #define all(x) (x).begin(),(x).end() #define outl(...) dump_func(__VA_ARGS__) #define outf(x) cout << fixed << setprecision(16) << (x) << endl #define inf 1e18 using namespace std; typedef long long llint; typedef long long ll; typedef pair P; struct edge{ ll to, cost; edge(){} edge(ll a, ll b){ to = a, cost = b;} }; const ll dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1}; const ll mod = 1000000007; //const ll mod = 998244353; struct mint{ ll x = 0; mint(ll y = 0){x = y; if(x < 0 || x >= mod) x = (x%mod+mod)%mod;} mint(const mint &ope) {x = ope.x;} mint operator-(){return mint(-x);} mint operator+(const mint &ope){return mint(x) += ope;} mint operator-(const mint &ope){return mint(x) -= ope;} mint operator*(const mint &ope){return mint(x) *= ope;} mint operator/(const mint &ope){return mint(x) /= ope;} mint& operator+=(const mint &ope){ x += ope.x; if(x >= mod) x -= mod; return *this; } mint& operator-=(const mint &ope){ x += mod - ope.x; if(x >= mod) x -= mod; return *this; } mint& operator*=(const mint &ope){ x *= ope.x, x %= mod; return *this; } mint& operator/=(const mint &ope){ ll n = mod-2; mint mul = ope; while(n){ if(n & 1) *this *= mul; mul *= mul; n >>= 1; } return *this; } mint inverse(){return mint(1) / *this;} bool operator ==(const mint &ope){return x == ope.x;} bool operator !=(const mint &ope){return x != ope.x;} }; mint modpow(mint a, ll n){ if(n == 0) return mint(1); if(n % 2) return a * modpow(a, n-1); else return modpow(a*a, n/2); } istream& operator >>(istream &is, mint &ope){ ll t; is >> t, ope.x = t; return is; } ostream& operator <<(ostream &os, mint &ope){return os << ope.x;} ostream& operator <<(ostream &os, const mint &ope){return os << ope.x;} vector fact, fact_inv; void make_fact(int n){ fact.resize(n+1), fact_inv.resize(n+1); fact[0] = mint(1); rep(i, 1, n) fact[i] = fact[i-1] * mint(i); fact_inv[n] = fact[n].inverse(); per(i, n-1, 0) fact_inv[i] = fact_inv[i+1] * mint(i+1); } mint comb(ll n, ll k){ if(n < 0 || k < 0 || n < k) return mint(0); return fact[n] * fact_inv[k] * fact_inv[n-k];} mint perm(ll n, ll k){ return comb(n, k) * fact[k]; } vector prime, pvec; void make_prime(int n){ prime.resize(n+1); rep(i, 2, n){ if(prime[i]) continue; for(int j = i; j <= n; j+=i) prime[j] = i; } rep(i, 2, n) if(prime[i] == i) pvec.push_back(i); } bool exceed(ll x, ll y, ll m){return x >= m / y + 1;} void mark(){ cout << "*" << endl; } void yes(){ cout << "YES" << endl; } void no(){ cout << "NO" << endl; } ll sgn(ll x){ if(x > 0) return 1; if(x < 0) return -1; return 0;} ll gcd(ll a, ll b){if(b == 0) return a; return gcd(b, a%b);} ll lcm(ll a, ll b){return a/gcd(a, b)*b;} ll digitnum(ll x, ll b = 10){ll ret = 0; for(; x; x /= b) ret++; return ret;} ll digitsum(ll x, ll b = 10){ll ret = 0; for(; x; x /= b) ret += x % b; return ret;} string lltos(ll x){string ret; for(;x;x/=10) ret += x % 10 + '0'; reverse(ret.begin(), ret.end()); return ret;} ll stoll(string &s){ll ret = 0; for(auto c : s) ret *= 10, ret += c - '0'; return ret;} template void uniq(T &vec){ sort(vec.begin(), vec.end()); vec.erase(unique(vec.begin(), vec.end()), vec.end());} template pair& operator+=(pair &s, const pair &t){ s.first += t.first, s.second += t.second; return s; } template pair& operator-=(pair &s, const pair &t){ s.first -= t.first, s.second -= t.second; return s; } template pair operator+(const pair &s, const pair &t){ return pair(s.first+t.first, s.second+t.second); } template pair operator-(const pair &s, const pair &t){ return pair(s.first-t.first, s.second-t.second); } template ostream& operator << (ostream& os, vector& vec) { for(int i = 0; i < vec.size(); i++) os << vec[i] << (i + 1 == vec.size() ? "" : " "); return os; } template ostream& operator << (ostream& os, deque& deq) { for(int i = 0; i < deq.size(); i++) os << deq[i] << (i + 1 == deq.size() ? "" : " "); return os; } template ostream& operator << (ostream& os, pair& pair_var) { os << "(" << pair_var.first << ", " << pair_var.second << ")"; return os; } template ostream& operator << (ostream& os, const pair& pair_var) { os << "(" << pair_var.first << ", " << pair_var.second << ")"; return os; } template ostream& operator << (ostream& os, map& map_var) { for(typename map::iterator itr = map_var.begin(); itr != map_var.end(); itr++) { os << "(" << itr->first << ", " << itr->second << ")"; itr++; if(itr != map_var.end()) os << ","; itr--; } return os; } template ostream& operator << (ostream& os, set& set_var) { for(typename set::iterator itr = set_var.begin(); itr != set_var.end(); itr++) { os << *itr; ++itr; if(itr != set_var.end()) os << " "; itr--; } return os; } template ostream& operator << (ostream& os, multiset& set_var) { for(typename multiset::iterator itr = set_var.begin(); itr != set_var.end(); itr++) { os << *itr; ++itr; if(itr != set_var.end()) os << " "; itr--; } return os; } template void outa(T a[], ll s, ll t){for(ll i = s; i <= t; i++){ cout << a[i]; if(i < t) cout << " ";}cout << endl;} void dump_func(){cout << endl;} template void dump_func(Head &&head, Tail &&... tail) { cout << head; if(sizeof...(Tail) > 0) cout << " "; dump_func(std::move(tail)...); } ll n, h, w; int main(void) { ios::sync_with_stdio(0); cin.tie(0); cin >> n >> h >> w; cout << (n/2)*ceil(n,2)*(h+w-2) << endl; return 0; }