#pragma GCC optimize("Ofast") #pragma GCC optimize("unroll-loops") #include using namespace std; using uint = unsigned int; using ll = long long; using ull = unsigned long long; using ld = long double; using i128 = __int128_t; template using fn = function; #define all(a) a.begin(), a.end() #define allr(a) a.rbegin(), a.rend() template int len(const A &a) { return a.size(); } #define eb emplace_back #define pb push_back #define elif else if template using vec = vector; template using vec2 = vec>; template using vec3 = vec>; template using vec4 = vec>; template using vec5 = vec>; #define VEC(T, a, ...) \ vec a(__VA_ARGS__) #define VEC2(T, a, n, ...) \ vector a(n, vec(__VA_ARGS__)); #define VEC3(T, a, n, m, ...) \ vector a( \ n, \ vector(m, vec(__VA_ARGS__)) \ ); #define VEC4(T, a, n, m, l, ...) \ vector a( \ n, \ vector( \ m, \ vector(l, vec(__VA_ARGS__)) \ ) \ ); #define eval_4(a, b, c, d, e, ...) e #define loop while (1) #define rep(n) \ for (int __ = 0; __ < n; __++) #define range_1(i, n) \ for (int i = 0; i < n; i++) #define range_2(i, a, b) \ for (ll i = a; i < b; i++) #define range_3(i, a, b, c) \ for (ll i = a; i < b; i += c) #define range(...) \ eval_4(__VA_ARGS__, range_3, range_2, range_1, rep)( \ __VA_ARGS__ \ ) #define ranger_1(i, n) \ for (int i = n; i-- > 0;) #define ranger_2(i, a, b) \ for (ll i = b; i-- > a;) #define ranger_3(i, a, b, c) \ for (ll i = b - 1; i >= a; i -= c) #define range_rev(...) \ eval_4(__VA_ARGS__, ranger_3, ranger_2, ranger_1)( \ __VA_ARGS__ \ ) #define iter(x, a) \ for (const auto &x : a) #define iter_mut(x, a) \ for (auto &&x : a) template istream & operator>>(istream &in, pair &p) { return in >> p.first >> p.second; } template ostream &operator<<( ostream &out, pair &p ) { out << p.first << ' ' << p.second; return out; } template void read_tup(istream &in, T &x) { if constexpr (tuple_size::value > k) { in >> get(x); read_tup(in, x); } } template istream &operator>>( istream &in, tuple &x ) { read_tup(in, x); return in; } template void out_tup(ostream &out, T &x) { if constexpr (tuple_size::value > k) { if constexpr (k > 0) { out << ' '; } out << get(x); out_tup(out, x); } } template ostream &operator<<( ostream &out, tuple &x ) { out_tup(out, x); return out; } template auto operator<<(ostream &out, vec a) -> ostream & { range(i, len(a)) { if (i) { out << ' '; } out << a[i]; } return out; } template auto operator<<(ostream &out, vec2 a) -> ostream & { iter_mut(x, a) out << x << '\n'; return out; } template auto operator>>(istream &in, vec &a) -> istream & { iter_mut(x, a) in >> x; return in; } template void in(T &...a) { (cin >> ... >> a); } template void out(T a, const U... b) { cout << a; ((cout << ' ' << b), ...); cout << '\n'; } template vec iota(int n, T v = 0) { vec a(n); std::iota(all(a), v); return a; } template using max_queue = priority_queue; template using min_queue = priority_queue, greater>; template T pop(queue &q) { T v = q.front(); q.pop(); return v; } template T pop(deque &q) { T v = q.front(); q.pop_front(); return v; } template T pop(vec &q) { T v = q.back(); q.pop_back(); return v; } template T pop(max_queue &q) { T v = q.top(); q.pop(); return v; } template T pop(min_queue &q) { T v = q.top(); q.pop(); return v; } template T max(const vec &a) { return *max_element(all(a)); } template T min(const vec &a) { return *min_element(all(a)); } int topbit(int x) { return 31 - __builtin_clz(x); } template bool operator==( const vec &a, const vec &b ) { int n = len(a); if (len(b) != n) { return false; } range(i, n) { if (a[i] != b[i]) { return false; } } return true; } template bool chmin(T &a, const U &b) { return b < a ? a = b, 1 : 0; } template bool chmax(T &a, const U &b) { return b > a ? a = b, 1 : 0; } int popcnt(int x) { return __builtin_popcount(x); } template T sum(const vec &a) { return accumulate(all(a), 0ll); } template void unique(vec &a) { sort(all(a)); a.erase(std::unique(all(a)), a.end()); } template int lb(const A &a, const T &x) { auto p = lower_bound(all(a), x); return distance(a.begin(), p); } template int ub(const A &a, const T &x) { auto p = upper_bound(all(a), x); return distance(a.begin(), p); } template vec argsort(const A &a) { int n = len(a); auto b = iota(n); sort(all(b), [&](int i, int j) { return a[i] < a[j]; }); return b; } template int ctz(T n) { return __builtin_ctzll(n); } template auto divmod(T a, T b) -> pair { T q = a / b; return {q, a - q * b}; } #ifdef DEBUG #define dbg(...) out(__VA_ARGS__); #else #define dbg(...) ; #endif #ifdef DEBUG #define dbg_assert(...) \ assert(__VA_ARGS__); #else #define dbg_assert(...) ; #endif // define yes/no #define yesno(y, n) \ void yes(bool f = 1) { \ out(f ? #y : #n); \ } \ void no() { \ out(#n); \ } yesno(yes, no); // yesno(Yes, No); // yesno(YES, NO); // const/runtime // id <= 0, call set_mod template class mint { ll v; static int mod; static constexpr int m() { return id > 0 ? id : mod; } public: static void set_mod(int m) { assert(m > 0); mod = m; } constexpr mint(): v() { } mint(ll v): v(v) { norm(); } void norm() { if (v < -m() || m() <= v) { v %= m(); } if (v < 0) { v += m(); } } int operator()() const { return v; } template explicit operator T() const { return static_cast(v); } mint operator-() const { return v ? m() - v : 0; } mint &operator+=(const mint &a) { if ((v += a.v) >= m()) { v -= m(); } return *this; } mint &operator-=(const mint &a) { if ((v -= a.v) < 0) { v += m(); } return *this; } mint &operator*=(const mint &a) { v *= a.v; norm(); return *this; } mint inv() const { int a = m(), b = v, u = 0, v = 1, q; while (b) { q = a / b; swap(u -= q * v, v); swap(a -= q * b, b); } return u; } mint pow(ll t) const { if (t < 0) { return inv().pow(-t); } mint y = 1, x(v); while (t) { if (t & 1) { y *= x; } x *= x; t >>= 1; } return y; } mint &operator/=(const mint &a) { return *this *= a.inv(); } auto operator++() -> mint & { return *this += 1; } auto operator--() -> mint & { return *this -= 1; } auto operator++(int) -> mint { mint a(*this); *this += 1; return a; } auto operator--(int) -> mint { mint a(*this); *this -= 1; return a; } friend mint operator+( const mint &a, const mint &b ) { return mint(a) += b; } friend mint operator-( const mint &a, const mint &b ) { return mint(a) -= b; } friend mint operator*( const mint &a, const mint &b ) { return mint(a) *= b; } friend mint operator/( const mint &a, const mint &b ) { return mint(a) /= b; } friend bool operator==( const mint &a, const mint &b ) { return a.v == b.v; } friend istream & operator>>(istream &i, mint &x) { i >> x.v; x.norm(); return i; } friend ostream &operator<<( ostream &o, const mint &x ) { return o << x.v; } }; template int mint::mod = 1; using mint107 = mint<1'000'000'007>; using mint998 = mint<998'244'353>; using mint_runtime = mint<0>; template T norm(T m, T x) { assert(m > 0); if (x < -m || x >= m) { x %= m; } if (x < 0) { x += m; } return x; } template tuple egcd(T a, T b) { if (!b) { if (a < 0) { return {-a, -1, 0}; } return {a, 1, 0}; }; T q = a / b; auto [g, x, y] = egcd(b, a - b * q); return {g, y, x - q * y}; } template pair ginv(T m, T a) { assert(0 < a && a < m); auto [g, x, _] = egcd(a, m); m /= g; if (x < 0) { x += m; } dbg_assert(0 <= x && x < m); return {g, x}; } int inv(int m, int a) { auto [g, x] = ginv(m, norm(m, a)); assert(g == 1); return x; } template class comb { public: vec f, fi, inv; comb(int n): f(n), fi(n), inv(n) { f[0] = 1; range(i, 1, n) { f[i] = f[i - 1] * i % m; } fi[n - 1] = ::inv(m, f[n - 1]); range_rev(i, 1, n) { fi[i - 1] = fi[i] * i % m; inv[i] = fi[i] * f[i - 1] % m; } } auto p(int n, int k) -> int { if (k < 0 || n < k) { return 0; } return f[n] * fi[n - k] % m; } auto c(int n, int k) -> int { if (k < 0 || n < k) { return 0; } return p(n, k) * fi[k] % m; } auto h(int n, int k) -> int { return c(n - 1 + k, k); } auto ip(int n, int k) -> int { assert(0 <= k && k <= n); return fi[n] * f[n - k] % m; } auto ic(int n, int k) -> int { return ip(n, k) * f[k] % m; } }; constexpr int mod = 998'244'353; void solve() { int x, y, z, w; in(x, y, z, w); chmax(z, 1); chmax(w, 1); // using mint = mint998; auto f = comb(1 << 20); ll res = f.f[x + y - z - w]; res *= f.c(x, z); res %= mod; res *= f.c(y, w); res %= mod; out(res); } int main() { ios::sync_with_stdio(0); cin.tie(0); // cout << setprecision(16); int t = 1; // in(t); while (t--) { solve(); } }