#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i = 0; i < (int)n; i++)

int main() {
  string n;
  cin >> n;
  vector<int> ns((int)n.size());
  int nn = (int)n.size();
  rep(i, nn)
    ns[i] =  n[i] - '0';
  bool ok = false;  
  while (!ok) {
    int m = 0;
    bool thr = false;
    rep(j, nn) {
      m = m * 10 + ns[j] % 3;
      if (ns[j] == 3)
	thr = true;
    }
    if (!thr && m % 3 != 0) {
      rep(j, nn)
	cout << ns[j];
      cout << endl;
      ok = true;
    } else {
      int j = nn - 1;
      ns[j]--;
      while (j > 0 && ns[j] < 0) {
	ns[j] += 10;
	j--;
	ns[j]--;
      }
    }
  }
  return 0;
}