#include <bits/stdc++.h>
using namespace std;
char s[100010], s1[100010], s2[100010], s3[100010], s11[100010];
int main() {
  scanf("%s", &s);
  int len;
  len = strlen(s);
  int sum = 0, a = 0;
  for (int i = 0; i < len; i++) {
    sum += s[i] - '0';
    if (s[i] == '0') a = 1;
  }
  if (sum % 3 == 0) {
    int cnt = 0;
    for (int i = 0; i < len - 1; i++) {
      if (s[i] != '0')
        break;
      else
        cnt++;
    }
    int j = 0;
    for (int i = cnt; i < len; i++) s1[j++] = s[i];
    cout << s1 << endl;
  } else {
    int num = sum % 3;
    int cnt1 = -1, cnt2 = -1, cnt3 = -1;
    int t1 = 0, t2 = 0;
    for (int i = len - 1; i >= 0; i--) {
      if ((s[i] - '0') % 3 == num) {
        cnt1 = i;
        break;
      }
    }
    if (cnt1 != -1) {
      int j = 0;
      for (int i = 0; i < len; i++) {
        if (i == cnt1)
          continue;
        else
          s1[j++] = s[i];
      }
      int cnt = 0;
      for (int i = 0; i < j - 1; i++) {
        if (s1[i] != '0')
          break;
        else
          cnt++;
      }
      for (int i = cnt; i < j; i++) s2[t1++] = s1[i];
    }
    for (int i = len - 1; i >= 1; i--) {
      if ((s[i] - '0') % 3 == 0) continue;
      for (int j = i - 1; j >= 0; j--) {
        int cnt = s[i] - '0' + s[j] - '0';
        if (cnt % 3 == num) {
          cnt2 = i;
          cnt3 = j;
          break;
        }
      }
      if (cnt2 != -1 && cnt3 != -1) break;
    }
    if (cnt2 != -1 && cnt3 != -1) {
      int j = 0;
      for (int i = 0; i < len; i++) {
        if (i == cnt2 || i == cnt3) continue;
        s11[j++] = s[i];
      }
      int cnt = 0;
      for (int i = 0; i < j - 1; i++) {
        if (s11[i] != '0')
          break;
        else
          cnt++;
      }
      for (int i = cnt; i < j; i++) s3[t2++] = s11[i];
    }
    if (!a && t1 == 0 && t2 == 0)
      cout << -1 << endl;
    else if (t1 == 0 && t2 == 0)
      cout << 0 << endl;
    else if (t1 >= t2)
      cout << s2 << endl;
    else
      cout << s3 << endl;
  }
  return 0;
}
