//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx")
//#undef LOCAL




#include <algorithm>

#include <array>

#include <bitset>

#include <cassert>

#include <complex>

#include <cstdio>

#include <cstring>

#include <iostream>

#include <map>

#include <numeric>

#include <queue>

#include <set>

#include <string>

#include <unordered_map>

#include <unordered_set>

#include <vector>

using namespace std;

using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); }
template <class T> using V = vector<T>;
template <class T> using VV = V<V<T>>;

struct Scanner {
    FILE* fp = nullptr;
    char line[(1 << 15) + 1];
    size_t st = 0, ed = 0;
    void reread() {
        memmove(line, line + st, ed - st);
        ed -= st;
        st = 0;
        ed += fread(line + ed, 1, (1 << 15) - ed, fp);
        line[ed] = '\0';
    }
    bool succ() {
        while (true) {
            if (st == ed) {
                reread();
                if (st == ed) return false;
            }
            while (st != ed && isspace(line[st])) st++;
            if (st != ed) break;
        }
        if (ed - st <= 50) reread();
        return true;
    }
    template <class T, enable_if_t<is_same<T, string>::value, int> = 0>
    bool read_single(T& ref) {
        if (!succ()) return false;
        while (true) {
            size_t sz = 0;
            while (st + sz < ed && !isspace(line[st + sz])) sz++;
            ref.append(line + st, sz);
            st += sz;
            if (!sz || st != ed) break;
            reread();
        }
        return true;
    }
    template <class T, enable_if_t<is_integral<T>::value, int> = 0>
    bool read_single(T& ref) {
        if (!succ()) return false;
        bool neg = false;
        if (line[st] == '-') {
            neg = true;
            st++;
        }
        ref = T(0);
        while (isdigit(line[st])) {
            ref = 10 * ref + (line[st++] - '0');
        }
        if (neg) ref = -ref;
        return true;
    }
    template <class T> bool read_single(V<T>& ref) {
        for (auto& d : ref) {
            if (!read_single(d)) return false;
        }
        return true;
    }
    void read() {}
    template <class H, class... T> void read(H& h, T&... t) {
        bool f = read_single(h);
        assert(f);
        read(t...);
    }
    Scanner(FILE* _fp) : fp(_fp) {}
};

struct Printer {
  public:
    template <bool F = false> void write() {}
    template <bool F = false, class H, class... T>
    void write(const H& h, const T&... t) {
        if (F) write_single(' ');
        write_single(h);
        write<true>(t...);
    }
    template <class... T> void writeln(const T&... t) {
        write(t...);
        write_single('\n');
    }

    Printer(FILE* _fp) : fp(_fp) {}
    ~Printer() { flush(); }

  private:
    static constexpr size_t SIZE = 1 << 15;
    FILE* fp;
    char line[SIZE], small[50];
    size_t pos = 0;
    void flush() {
        fwrite(line, 1, pos, fp);
        pos = 0;
    }
    void write_single(const char& val) {
        if (pos == SIZE) flush();
        line[pos++] = val;
    }
    template <class T, enable_if_t<is_integral<T>::value, int> = 0>
    void write_single(T val) {
        if (pos > (1 << 15) - 50) flush();
        if (val == 0) {
            write_single('0');
            return;
        }
        if (val < 0) {
            write_single('-');
            val = -val; // todo min
        }
        size_t len = 0;
        while (val) {
            small[len++] = char('0' + (val % 10));
            val /= 10;
        }
        for (size_t i = 0; i < len; i++) {
            line[pos + i] = small[len - 1 - i];
        }
        pos += len;
    }
    void write_single(const string& s) {
        for (char c : s) write_single(c);
    }
    void write_single(const char* s) {
        size_t len = strlen(s);
        for (size_t i = 0; i < len; i++) write_single(s[i]);
    }
    template <class T> void write_single(const V<T>& val) {
        auto n = val.size();
        for (size_t i = 0; i < n; i++) {
            if (i) write_single(' ');
            write_single(val[i]);
        }
    }
};


template <uint MD> struct ModInt {
    using M = ModInt;
    static constexpr uint get_mod() { return MD; }
    const static M G;
    uint v;
    ModInt(ll _v = 0) { set_v(uint(_v % MD + MD)); }
    M& set_v(uint _v) {
        v = (_v < MD) ? _v : _v - MD;
        return *this;
    }
    explicit operator bool() const { return v != 0; }
    M operator-() const { return M() - *this; }
    M operator+(const M& r) const { return M().set_v(v + r.v); }
    M operator-(const M& r) const { return M().set_v(v + MD - r.v); }
    M operator*(const M& r) const { return M().set_v(uint(ull(v) * r.v % MD)); }
    M operator/(const M& r) const { return *this * r.inv(); }
    M& operator+=(const M& r) { return *this = *this + r; }
    M& operator-=(const M& r) { return *this = *this - r; }
    M& operator*=(const M& r) { return *this = *this * r; }
    M& operator/=(const M& r) { return *this = *this / r; }
    bool operator==(const M& r) const { return v == r.v; }
    M pow(ll n) const {
        M x = *this, r = 1;
        while (n) {
            if (n & 1) r *= x;
            x *= x;
            n >>= 1;
        }
        return r;
    }
    M inv() const { return pow(MD - 2); }
    friend ostream& operator<<(ostream& os, const M& r) { return os << r.v; }
};
// using Mint = ModInt<998244353>;
// template<> const Mint Mint::G = Mint(3);


template<class Mint>
struct Comb {
    int max_n;
    V<Mint> fact, ifact;
    Comb() {}
    Comb(int n) : max_n(n) {
        fact = ifact = V<Mint>(n + 1);
        fact[0] = Mint(1);
        for (int i = 1; i <= n; i++) fact[i] = fact[i - 1] * i;
        ifact[n] = fact[n].inv();
        for (int i = n; i >= 1; i--) ifact[i - 1] = ifact[i] * i;
    }

    Mint C(int n, int k) {
        if (n < k || n < 0) return Mint(0);
        assert(0 <= k && k <= n && n <= max_n);
        return fact[n] * ifact[k] * ifact[n - k];
    }
};

using Mint = ModInt<998244353>;

Scanner sc = Scanner(stdin);
Printer pr = Printer(stdout);

Comb<Mint> C(10000);

V<Mint> p2(TEN(4));

void init() {
    p2[0] = Mint(1);
    for (int i = 1; i < TEN(4); i++) {
        p2[i] = p2[i - 1] * Mint(2);
    }
}

int n;
V<int> h;
using DP = V<array<Mint, 2>>;
DP solve(int l, int r, int s) {
    if (l == r) return DP(s + 1, {Mint(1), Mint(1)});

    int mi = TEN(9);
    V<int> pos;
    for (int i = l; i < r; i++) {
        if (h[i] < mi) {
            mi = h[i];
            pos = {i};
        } else if (h[i] == mi) {
            pos.push_back(i);
        }
    }
    int k = int(pos.size());

    int bk = l;
    pos.push_back(r);
    DP dp(mi + 1, {Mint(1), Mint(1)});
    for (int x : pos) {
        auto cdp = solve(bk, x, mi);
        for (int i = 0; i <= mi; i++) {
            dp[i][0] *= cdp[i][0];
            dp[i][1] *= cdp[i][1];
        }
        bk = x + 1;
    }

    for (int ph = 0; ph < k; ph++) {
        for (int i = 0; i <= mi; i++) {
            for (int j = 0; j <= 1; j++) {
                Mint w = 0;
                w -= dp[i][j]; // y-line
                w += dp[i][j] * p2[i]; // xy-line
                if (j == 0) w += dp[i][j]; // zy-line
                dp[i][j] = w;
            }
        }
    }

    for (int ph = mi - 1; ph >= s; ph--) {
        DP ndp(ph + 1);
        for (int i = 0; i <= ph; i++) {
            for (int j = 0; j <= 1; j++) {
                ndp[i][j] -= dp[i][j]; // y-line
                ndp[i][j] += dp[i + 1][j]; // xy-line
                ndp[i][j] += dp[i][1]; // zy-line
            }
        }
        dp = ndp;
    }

    return dp;
}

int main() {
    init();
    sc.read(n);
    h = V<int>(n);
    for (int i = 0; i < n; i++) {
        sc.read(h[i]);
    }

    auto res = solve(0, n, 0);
            ;
    pr.writeln(res[0][0].v);
    return 0;
}


Measured memory_bytes: 1024