#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const int INF = (int)1e9;
const long long LINF = (long long)1e18;
const long double PI = acos((long double)-1);
const long double EPS = 1e-9;
inline long long gcd(long long a, long long b) {
  long long r;
  while (b) {
    r = a % b;
    a = b;
    b = r;
  }
  return a;
}
inline long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
inline long long fpow(long long n, long long k, int p = MOD) {
  long long r = 1;
  for (; k; k >>= 1) {
    if (k & 1) r = r * n % p;
    n = n * n % p;
  }
  return r;
}
template <class T>
inline int chkmin(T& a, const T& val) {
  return val < a ? a = val, 1 : 0;
}
template <class T>
inline int chkmax(T& a, const T& val) {
  return a < val ? a = val, 1 : 0;
}
inline long long isqrt(long long k) {
  long long r = sqrt(k) + 1;
  while (r * r > k) r--;
  return r;
}
inline long long icbrt(long long k) {
  long long r = cbrt(k) + 1;
  while (r * r * r > k) r--;
  return r;
}
inline void addmod(int& a, int val, int p = MOD) {
  if ((a = (a + val)) >= p) a -= p;
}
inline void submod(int& a, int val, int p = MOD) {
  if ((a = (a - val)) < 0) a += p;
}
inline int mult(int a, int b, int p = MOD) { return (long long)a * b % p; }
inline int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }
inline int sign(long double x) { return x < -EPS ? -1 : x > +EPS; }
inline int sign(long double x, long double y) { return sign(x - y); }
string strmax(string a, string b) {
  if (a == "") a = "-1";
  if (b == "") b = "-1";
  if (a == "-1") return b;
  if (b == "-1") return a;
  if (int((a).size()) > int((b).size())) return a;
  return b;
}
string work1(string s) {
  vector<int> v[3];
  int sum = 0;
  for (int i = (0); i < (int((s).size())); i++) {
    int k = s[i] - '0';
    if (i) {
      v[k % 3].push_back(i);
    }
    sum = (sum + k) % 3;
  }
  if (!sum) {
    return s;
  }
  if (int((v[sum]).size())) {
    string t = s;
    t.erase(t.begin() + v[sum][0]);
    return t;
  }
  sum = (sum + sum) % 3;
  if (int((v[sum]).size()) > 1) {
    string t = s;
    t.erase(t.begin() + v[sum][1]);
    t.erase(t.begin() + v[sum][0]);
    return t;
  }
  return "-1";
}
string work2(string s, int step) {
  if (!int((s).size())) return "-1";
  if (step == 5) return "-1";
  s = s.substr(1);
  reverse((s).begin(), (s).end());
  while (int((s).size()) > 1 && s[int((s).size()) - 1] == '0') s.pop_back();
  reverse((s).begin(), (s).end());
  return strmax(work1(s), work2(s, step + 1));
}
void solve() {
  string s;
  cin >> s;
  string ans = work1(s);
  ans = strmax(ans, work2(s, 0));
  for (int i = (0); i < (int((s).size())); i++) {
    if (s[i] == '0') {
      ans = strmax(ans, "0");
    }
  }
  cout << ans << "\n";
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  solve();
  return 0;
}
