#include <bits/stdc++.h>
constexpr int kMod = 998244353;
template <typename T>
T add(T a, T b) {
  return (a + b) % kMod;
}
template <typename T, typename... Args>
T add(T a, T b, Args... args) {
  return add(add(a, b), args...);
}
template <typename T>
T sub(T a, T b) {
  return (a + kMod - b) % kMod;
}
template <typename T, typename... Args>
T sub(T a, T b, Args... args) {
  return sub(sub(a, b), args...);
}
template <typename T>
T mul(T a, T b) {
  return a * static_cast<long long>(b) % kMod;
}
template <typename T, typename... Args>
T mul(T a, T b, Args... args) {
  return mul(mul(a, b), args...);
}
template <typename T>
void Add(T &a, T b) {
  a = add(a, b);
}
template <typename T, typename... Args>
void Add(T &a, T b, Args... args) {
  Add(a, add(b, args...));
}
template <typename T>
void Sub(T &a, T b) {
  a = sub(a, b);
}
template <typename T, typename... Args>
void Sub(T &a, T b, Args... args) {
  Sub(a, add(b, args...));
}
template <typename T>
void Mul(T &a, T b) {
  a = mul(a, b);
}
template <typename T, typename... Args>
void Mul(T &a, T b, Args... args) {
  Mul(a, mul(b, args...));
}
template <typename T1, typename T2>
T1 Ksm(T1 a, T2 b) {
  T1 s = 1;
  while (b) {
    if (b & 1) Mul(s, a);
    Mul(a, a);
    b >>= 1;
  }
  return s;
}
int fac[1000001], inv[1000001], iv[1000001];
void Init(int n) {
  fac[0] = 1;
  for (int i = 1; i <= n; i++) fac[i] = mul(fac[i - 1], i);
  inv[n] = Ksm(fac[n], kMod - 2);
  for (int i = n - 1; i >= 0; i--) inv[i] = mul(inv[i + 1], i + 1);
  iv[0] = iv[1] = 1;
  for (int i = 2; i <= n; i++) iv[i] = mul(kMod - kMod / i, iv[kMod % i]);
}
int C(int x, int y) {
  if (x < y || y < 0) return 0;
  return mul(fac[x], inv[x - y], inv[y]);
}
template <typename T>
void checkmax(T &x, T y) {
  if (x < y) x = y;
}
template <typename T>
void checkmin(T &x, T y) {
  if (x > y) x = y;
}
template <class T, typename = decltype(std::declval<T>().begin()),
          typename = decltype(std::declval<T>().end()),
          typename = typename std::enable_if<!std::is_base_of<
              std::string, typename std::decay<T>::type>::value>::type,
          typename value_type = typename T::value_type>
std::ostream &operator<<(std::ostream &out, const T &container) {
  for (auto it = container.begin(); it != container.end(); ++it)
    out << *it << ' ';
  return out;
}
std::ostream &operator<<(std::ostream &out, __int128_t x) {
  static int s[101], top;
  top = 0;
  while (x) s[top++] = x % 10, x /= 10;
  for (int i = top - 1; i >= 0; i--) out << s[i];
  return out;
}
int n, a[200001], s[200001], stk[200001], top, s2[200001], pre[200001];
int main(int argc, char const *argv[]) {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(nullptr), std::cout.tie(nullptr);
  std::cin >> n;
  for (int i = 1; i <= n; i++) std::cin >> a[i];
  for (int i = 1; i <= n; i++) {
    while (top && a[stk[top]] > a[i]) top--;
    pre[i] = stk[top];
    stk[++top] = i;
  }
  s[0] = s2[0] = 1;
  for (int i = 1; i <= n; i++) {
    int f = sub(s2[i - 1], pre[i] ? s2[pre[i] - 1] : 0);
    if (~i & 1) f = (kMod - f) % kMod;
    s[i] = mul(f, a[i]);
    int dis = i - pre[i];
    if (pre[i]) {
      if (dis & 1)
        Sub(s[i], s[pre[i]]);
      else
        Add(s[i], s[pre[i]]);
    }
    if (i & 1)
      s2[i] = sub(s2[i - 1], s[i]);
    else
      s2[i] = add(s2[i - 1], s[i]);
  }
  std::cout << s[n];
  return 0;
}

### Prompt

Your challenge is to write a cpp solution to the following problem:

You are given an array of n positive integers a_1, a_2, …, a_n. Your task is to calculate the number of arrays of n positive integers b_1, b_2, …, b_n such that: 

  * 1 ≤ b_i ≤ a_i for every i (1 ≤ i ≤ n), and 
  * b_i ≠ b_{i+1} for every i (1 ≤ i ≤ n - 1). 



The number of such arrays can be very large, so print it modulo 998 244 353.

Input

The first line contains a single integer n (1 ≤ n ≤ 2 ⋅ 10^5) — the length of the array a.

The second line contains n integers a_1, a_2, …, a_n (1 ≤ a_i ≤ 10^9).

Output

Print the answer modulo 998 244 353 in a single line.

Examples

Input


3
2 2 2


Output


2

Input


2
2 3


Output


4

Input


3
1 1 1


Output


0

Note

In the first test case possible arrays are [1, 2, 1] and [2, 1, 2].

In the second test case possible arrays are [1, 2], [1, 3], [2, 1] and [2, 3].

### Response

```cpp
#include <bits/stdc++.h>
constexpr int kMod = 998244353;
template <typename T>
T add(T a, T b) {
  return (a + b) % kMod;
}
template <typename T, typename... Args>
T add(T a, T b, Args... args) {
  return add(add(a, b), args...);
}
template <typename T>
T sub(T a, T b) {
  return (a + kMod - b) % kMod;
}
template <typename T, typename... Args>
T sub(T a, T b, Args... args) {
  return sub(sub(a, b), args...);
}
template <typename T>
T mul(T a, T b) {
  return a * static_cast<long long>(b) % kMod;
}
template <typename T, typename... Args>
T mul(T a, T b, Args... args) {
  return mul(mul(a, b), args...);
}
template <typename T>
void Add(T &a, T b) {
  a = add(a, b);
}
template <typename T, typename... Args>
void Add(T &a, T b, Args... args) {
  Add(a, add(b, args...));
}
template <typename T>
void Sub(T &a, T b) {
  a = sub(a, b);
}
template <typename T, typename... Args>
void Sub(T &a, T b, Args... args) {
  Sub(a, add(b, args...));
}
template <typename T>
void Mul(T &a, T b) {
  a = mul(a, b);
}
template <typename T, typename... Args>
void Mul(T &a, T b, Args... args) {
  Mul(a, mul(b, args...));
}
template <typename T1, typename T2>
T1 Ksm(T1 a, T2 b) {
  T1 s = 1;
  while (b) {
    if (b & 1) Mul(s, a);
    Mul(a, a);
    b >>= 1;
  }
  return s;
}
int fac[1000001], inv[1000001], iv[1000001];
void Init(int n) {
  fac[0] = 1;
  for (int i = 1; i <= n; i++) fac[i] = mul(fac[i - 1], i);
  inv[n] = Ksm(fac[n], kMod - 2);
  for (int i = n - 1; i >= 0; i--) inv[i] = mul(inv[i + 1], i + 1);
  iv[0] = iv[1] = 1;
  for (int i = 2; i <= n; i++) iv[i] = mul(kMod - kMod / i, iv[kMod % i]);
}
int C(int x, int y) {
  if (x < y || y < 0) return 0;
  return mul(fac[x], inv[x - y], inv[y]);
}
template <typename T>
void checkmax(T &x, T y) {
  if (x < y) x = y;
}
template <typename T>
void checkmin(T &x, T y) {
  if (x > y) x = y;
}
template <class T, typename = decltype(std::declval<T>().begin()),
          typename = decltype(std::declval<T>().end()),
          typename = typename std::enable_if<!std::is_base_of<
              std::string, typename std::decay<T>::type>::value>::type,
          typename value_type = typename T::value_type>
std::ostream &operator<<(std::ostream &out, const T &container) {
  for (auto it = container.begin(); it != container.end(); ++it)
    out << *it << ' ';
  return out;
}
std::ostream &operator<<(std::ostream &out, __int128_t x) {
  static int s[101], top;
  top = 0;
  while (x) s[top++] = x % 10, x /= 10;
  for (int i = top - 1; i >= 0; i--) out << s[i];
  return out;
}
int n, a[200001], s[200001], stk[200001], top, s2[200001], pre[200001];
int main(int argc, char const *argv[]) {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(nullptr), std::cout.tie(nullptr);
  std::cin >> n;
  for (int i = 1; i <= n; i++) std::cin >> a[i];
  for (int i = 1; i <= n; i++) {
    while (top && a[stk[top]] > a[i]) top--;
    pre[i] = stk[top];
    stk[++top] = i;
  }
  s[0] = s2[0] = 1;
  for (int i = 1; i <= n; i++) {
    int f = sub(s2[i - 1], pre[i] ? s2[pre[i] - 1] : 0);
    if (~i & 1) f = (kMod - f) % kMod;
    s[i] = mul(f, a[i]);
    int dis = i - pre[i];
    if (pre[i]) {
      if (dis & 1)
        Sub(s[i], s[pre[i]]);
      else
        Add(s[i], s[pre[i]]);
    }
    if (i & 1)
      s2[i] = sub(s2[i - 1], s[i]);
    else
      s2[i] = add(s2[i - 1], s[i]);
  }
  std::cout << s[n];
  return 0;
}

```