Problem: Vitya is studying in the third grade. During the last math lesson all the pupils wrote on arithmetic quiz. Vitya is a clever boy, so he managed to finish all the tasks pretty fast and Oksana Fillipovna gave him a new one, that is much harder.

Let's denote a flip operation of an integer as follows: number is considered in decimal notation and then reverted. If there are any leading zeroes afterwards, they are thrown away. For example, if we flip 123 the result is the integer 321, but flipping 130 we obtain 31, and by flipping 31 we come to 13.

Oksana Fillipovna picked some number a without leading zeroes, and flipped it to get number ar. Then she summed a and ar, and told Vitya the resulting value n. His goal is to find any valid a.

As Oksana Fillipovna picked some small integers as a and ar, Vitya managed to find the answer pretty fast and became interested in finding some general algorithm to deal with this problem. Now, he wants you to write the program that for given n finds any a without leading zeroes, such that a + ar = n or determine that such a doesn't exist.

Input

The first line of the input contains a single integer n (1 ≤ n ≤ 10100 000).

Output

If there is no such positive integer a without leading zeroes that a + ar = n then print 0. Otherwise, print any valid a. If there are many possible answers, you are allowed to pick any.

Examples

Input

4


Output

2


Input

11


Output

10


Input

5


Output

0


Input

33


Output

21

Note

In the first sample 4 = 2 + 2, a = 2 is the only possibility.

In the second sample 11 = 10 + 1, a = 10 — the only valid solution. Note, that a = 01 is incorrect, because a can't have leading zeroes.

It's easy to check that there is no suitable a in the third sample.

In the fourth sample 33 = 30 + 3 = 12 + 21, so there are three possibilities for a: a = 30, a = 12, a = 21. Any of these is considered to be correct answer.

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline int checkbit(T n, T i) {
  return ((n >> i) & T(1));
}
inline int bits_count(int v) {
  v = v - ((v >> 1) & 0x55555555);
  v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
  return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
}
inline int bits_count(long long v) {
  int t = v >> 32;
  int p = (v & ((1LL << 32) - 1));
  return bits_count(t) + bits_count(p);
}
unsigned int reverse_bits(register unsigned int x) {
  x = (((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1));
  x = (((x & 0xcccccccc) >> 2) | ((x & 0x33333333) << 2));
  x = (((x & 0xf0f0f0f0) >> 4) | ((x & 0x0f0f0f0f) << 4));
  x = (((x & 0xff00ff00) >> 8) | ((x & 0x00ff00ff) << 8));
  return ((x >> 16) | (x << 16));
}
template <typename T>
inline bool isPowerOfTwo(T n) {
  return (n != 0 and ((n & (n - 1)) == 0));
}
inline int binlog(int n) {
  assert(n > 0);
  return 32 - __builtin_clz(n) - 1;
}
inline int binlog(long long n) {
  assert(n > 0);
  return 64 - __builtin_clzll(n) - 1;
}
void bitprint(int n, int w = 32) {
  for (int i = w - 1; i >= 0; i--) {
    cout << checkbit(n, i);
  }
  cout << "\n";
}
void bitprint(long long n, int w = 64) {
  for (long long i = w - 1; i >= 0; i--) {
    cout << checkbit(n, i);
  }
  cout << "\n";
}
template <typename T>
inline T sqr(T x) {
  T x_ = (x);
  return x_ * x_;
}
template <typename T>
inline T qbr(T x) {
  T x_ = (x);
  return ((x_ * x_) * x_);
}
template <typename T>
inline int sign(T x) {
  T x_ = (x);
  return ((x_ > T(0)) - (x_ < T(0)));
}
template <typename T>
inline T mod(T x, T m) {
  T x_ = (x);
  return (((x_) >= 0) ? ((x_) % (m)) : ((((x_) % (m)) + (m)) % (m)));
}
template <typename T>
inline T gcd(T a, T b) {
  while (b) {
    T t = a % b;
    a = b;
    b = t;
  }
  return a;
}
template <typename T>
inline T gcd_ex(T a, T b, T& x, T& y) {
  if (b == 0) {
    x = 1, y = 0;
    return a;
  }
  T x1, y1;
  T d = gcd_ex(b, a % b, x1, y1);
  x = y1;
  y = x1 - (a / b) * y1;
  return d;
}
template <typename T>
inline T lcm(T a, T b) {
  return (a * (b / gcd(a, b)));
}
template <typename A, typename B, typename C>
function<C(A)> combine(function<B(A)> f, function<C(B)> g) {
  return bind(g, bind(f, placeholders::_1));
}
template <typename Collection, typename UnaryOperation>
void foreach (Collection& col, UnaryOperation op) {
  for_each(begin(col), end(col), op);
}
template <typename Collection, typename UnaryOperation>
Collection fmap(Collection& col, UnaryOperation op) {
  transform(begin(col), end(col), col.begin(), op);
  return col;
}
template <typename Collection, typename binop>
Collection zip(Collection& fc, Collection& sc, binop op) {
  transform(begin(fc), end(fc), sc.begin(), fc.begin(), op);
  return fc;
}
template <typename Collection, typename Condition>
bool exists(Collection& col, Condition con) {
  auto exist = find_if(begin(col), end(col), con);
  return exist != col.end();
}
template <typename Collection, typename Predicate>
Collection filterNot(Collection& col, Predicate predicate) {
  auto returnIterator = remove_if(begin(col), end(col), predicate);
  col.erase(returnIterator, end(col));
  return col;
}
void fastIO() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
}
template <class T1, class T2>
istream& operator>>(istream& in, pair<T1, T2>& P) {
  in >> P.first >> P.second;
  return in;
}
template <class T>
istream& operator>>(istream& in, vector<T>& Col) {
  for (auto& el : Col) in >> el;
  return in;
}
template <class T>
inline void getarr(T* arr, int l, int r) {
  for (long long i = l; i < r; i++) cin >> arr[i];
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
  for (auto& row : v) {
    for (auto& el : row) os << el << " ";
    os << "\n";
  }
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& Col) {
  for (auto& el : Col) os << el << " ";
  return os;
}
template <class T>
ostream& operator<<(ostream& os, const set<T>& Col) {
  for (auto& el : Col) os << el << " ";
  return os;
}
template <class T1, class T2>
ostream& operator<<(ostream& os, const map<T1, T2>& Col) {
  for (auto& el : Col) os << el << " ";
  return os;
}
template <class T>
inline void printarr(T* arr, int l, int r) {
  for (long long i = l; i < r; i++) {
    cout << arr[i] << " ";
  };
  cout << "\n";
}
template <typename First>
void read(First& t) {
  cin >> t;
}
template <typename First, typename... Args>
void read(First& f, Args&... args) {
  cin >> f;
  read(forward<Args&>(args)...);
}
template <typename T>
void print(T&& t) {
  cout << t << "\n";
}
template <typename First, typename... Args>
void print(First&& f, Args&&... args) {
  cout << f << " ";
  print(forward<Args&&>(args)...);
}
template <typename T>
void printLn(T&& t) {
  cout << t << "\n";
}
template <typename First, typename... Args>
void printLn(First&& f, Args&&... args) {
  cout << f << "\n";
  printLn(forward<Args&&>(args)...);
}
template <typename T, size_t N>
struct MakeTensor {
  template <typename... Args>
  static auto tensor(size_t first, Args... sizes)
      -> vector<decltype(MakeTensor<T, N - 1>::tensor(sizes...))> {
    auto inner = MakeTensor<T, N - 1>::tensor(sizes...);
    return vector<decltype(inner)>(first, inner);
  }
};
template <typename T>
struct MakeTensor<T, 1> {
  static vector<T> tensor(size_t size) { return vector<T>(size); }
};
template <typename T, typename... Args>
auto tensor(Args... args)
    -> decltype(MakeTensor<T, sizeof...(Args)>::tensor(args...)) {
  return MakeTensor<T, sizeof...(Args)>::tensor(args...);
}
const int MAXN = 1e5;
char X[MAXN + 1];
int S[MAXN + 1], A[MAXN + 1];
int len;
inline void NO() {
  puts("0");
  exit(0);
}
bool restored() {
  int L, R;
  for (L = 1, R = len; L <= R;) {
    if (S[L] == S[R]) {
      L++, R--;
    } else if (S[L] == S[R] + 1 || S[L] == S[R] + 11) {
      S[L]--, S[L + 1] += 10;
    } else if (S[L] == S[R] + 10) {
      S[R - 1]--, S[R] += 10;
    } else
      return false;
  }
  if (S[1] == 0) return false;
  if (L - 1 == R + 1 && (S[L - 1] & 1)) return false;
  for (L = 1, R = len; L <= R; L++, R--) {
    if (S[L] > 18 || S[L] < 0) return false;
    A[L] = (S[L] + 1) >> 1;
    A[R] = S[L] - A[L];
  }
  for (int i = 1; i <= len; i++) printf("%c", A[i] + '0');
  return true;
}
int main() {
  fastIO();
  scanf("%s", X + 1);
  for (int i = 1; X[i]; i++) {
    S[i] = X[i] - '0';
    len++;
  }
  if (restored()) exit(0);
  if (X[1] != '1' || len == 1) NO();
  for (int i = 1; X[i]; i++) {
    S[i - 1] = X[i] - '0';
  }
  S[1] += 10;
  len--;
  if (restored()) exit(0);
  NO();
  return 0;
}