#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline bool upmin(T &x, T y) {
  return y < x ? x = y, 1 : 0;
}
template <typename T>
inline bool upmax(T &x, T y) {
  return x < y ? x = y, 1 : 0;
}
const long double eps = 1e-11;
const long double pi = acos(-1);
const int oo = 1 << 30;
const long long loo = 1ll << 62;
const int mods = 1e9 + 7;
const int MAXN = 200005;
const int INF = 0x3f3f3f3f;
inline int read() {
  int f = 1, x = 0;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = (x << 3) + (x << 1) + (c ^ 48);
    c = getchar();
  }
  return x * f;
}
char st[MAXN];
int a[MAXN], ans[MAXN];
signed main() {
  scanf("%s", st + 1);
  int n = strlen(st + 1);
  for (int i = 1; i <= n; i++) a[i] = st[i] - '0';
  int l = 1, r = n, flag = 0;
  if (a[l] != a[r]) a[l]--, a[l + 1] += 10, l += (!a[l]);
  while (l <= r) {
    if (a[l] != a[r]) {
      if (a[l] - a[r] >= 10) a[r] += 10, a[r - 1]--;
      if (a[l] - a[r] >= 1) a[l]--, a[l + 1] += 10;
    }
    if (a[l] != a[r]) {
      flag = 1;
      break;
    }
    ans[l] = a[l] - a[l] / 2, ans[r] = a[l] - ans[l];
    if (l == r) {
      flag = (a[l] & 1);
      break;
    }
    if (ans[l] < 0 || ans[l] > 9 || ans[r] < 0 || ans[r] > 9) {
      flag = 1;
      break;
    }
    l++, r--;
  }
  if (flag) {
    puts("0");
    return 0;
  }
  int p = 1;
  while (!ans[p]) p++;
  for (int i = p; i <= n; i++) printf("%d", ans[i]);
  return 0;
}
