#include <bits/stdc++.h>
using namespace std;
using db = double;
using ll = long long;
using ull = unsigned long long;
using pII = pair<int, int>;
using pLL = pair<ll, ll>;
constexpr int mod = 998244353;
template <class T1, class T2>
inline void chadd(T1 &x, T2 y, int Mod = mod) {
  x += y;
  while (x >= Mod) x -= Mod;
  while (x < 0) x += Mod;
}
template <class T1, class T2>
inline void chmax(T1 &x, T2 y) {
  if (x < y) x = y;
}
template <class T1, class T2>
inline void chmin(T1 &x, T2 y) {
  if (x > y) x = y;
}
inline int nextInt() {
  int x;
  cin >> x;
  return x;
}
void rd() {}
template <class T, class... Ts>
void rd(T &arg, Ts &...args) {
  cin >> arg;
  rd(args...);
}
void err() {
  cout << "\033[39;0m"
       << "\n";
}
template <class T, class... Ts>
void err(const T &arg, const Ts &...args) {
  cout << arg << ' ';
  err(args...);
}
template <template <typename...> class T, typename t, typename... A>
void err(const T<t> &arg, const A &...args) {
  for (auto &v : arg) cout << v << ' ';
  err(args...);
}
void ptt() { cout << "\n"; }
template <class T, class... Ts>
void ptt(const T &arg, const Ts &...args) {
  cout << ' ' << arg;
  ptt(args...);
}
template <class T, class... Ts>
void pt(const T &arg, const Ts &...args) {
  cout << arg;
  ptt(args...);
}
void pt() {}
template <template <typename...> class T, typename t, typename... A>
void pt(const T<t> &arg, const A &...args) {
  for (int i = 0, sze = arg.size(); i < sze; ++i)
    cout << arg[i] << " \n"[i == sze - 1];
  pt(args...);
}
inline ll qpow(ll base, ll n) {
  assert(n >= 0);
  ll res = 1;
  while (n) {
    if (n & 1) res = res * base % mod;
    base = base * base % mod;
    n >>= 1;
  }
  return res;
}
ll n, m, L, R, inv2 = (mod + 1) / 2;
void run() {
  if (n * m & 1) return pt(qpow(R - L + 1, n * m));
  ll even = (R / 2) - (L - 1) / 2;
  ll odd = (R - L + 1) - even;
  ll a = qpow(even + odd, n * m);
  ll b = qpow(even - odd, n * m);
  if (n * m % 2 == 0)
    pt((a + b) * inv2 % mod);
  else
    pt((a - b + mod) * inv2 % mod);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  cout << fixed << setprecision(20);
  while (cin >> n >> m >> L >> R) run();
  return 0;
}
