#include <bits/stdc++.h>
using namespace std;
char s[100010], ch[100010], ch1[100010], ch2[100010];
int main() {
  scanf("%s", s);
  int len = strlen(s), sum = 0, flag = 0;
  for (int i = 0; i < len; i++) {
    sum += s[i] - '0';
    if (s[i] == '0') flag = 1;
  }
  int tmp = sum % 3;
  if (tmp == 0) {
    int nu = 0, j = 0;
    while (nu < len - 1 && s[nu] == '0') {
      nu++;
    }
    for (int i = nu; i <= len - 1; i++) ch[j++] = s[i];
    printf("%s\n", ch);
  } else {
    int p1 = -1, p2 = -1, p3 = -1;
    for (int i = len - 1; i >= 0; i--) {
      if ((s[i] - '0') % 3 == tmp) {
        p1 = i;
        break;
      }
    }
    for (int i = len - 1; i >= 1; i--) {
      if ((s[i] - '0') % 3 == 0) continue;
      for (int j = i - 1; j >= 0; j--) {
        int x = s[i] - '0' + s[j] - '0';
        if (x % 3 == tmp) {
          p2 = i;
          p3 = j;
          break;
        }
      }
      if (p2 != -1 && p3 != -1) break;
    }
    int x1 = 0, x2 = 0;
    if (p1 != -1) {
      int j = 0, nu = 0;
      for (int i = 0; i <= len - 1; i++) {
        if (i == p1) continue;
        ch[j++] = s[i];
      }
      while (nu < j - 1 && ch[nu] == '0') {
        nu++;
      }
      for (int i = nu; i <= j - 1; i++) ch1[x1++] = ch[i];
    }
    if (p2 != -1 && p3 != -1) {
      int j = 0, nu = 0;
      for (int i = 0; i <= len - 1; i++) {
        if (i == p2 || i == p3) continue;
        ch[j++] = s[i];
      }
      while (nu < j - 1 && ch[nu] == '0') {
        nu++;
      }
      for (int i = nu; i <= j - 1; i++) ch2[x2++] = ch[i];
    }
    if (!flag && x1 == 0 && x2 == 0)
      printf("-1\n");
    else if (x1 == 0 && x2 == 0)
      printf("0\n");
    else if (x1 >= x2)
      printf("%s\n", ch1);
    else
      printf("%s\n", ch2);
  }
  return 0;
}
