#include <bits/stdc++.h>
using namespace std;
int dp[100005][4];
int n, t;
char s[100005];
int dfs(int node, int mod) {
  int ret1 = 2000000000, ret2;
  int nzero;
  if (node > n) {
    return dp[node][mod] = !mod ? 0 : 2000000000;
  }
  if (~dp[node][mod]) return dp[node][mod];
  if (t || s[node] != '0') {
    t++;
    ret1 = dfs(node + 1, (mod + s[node] - '0') % 3);
    t--;
  }
  ret2 = dfs(node + 1, mod) + 1;
  return dp[node][mod] = min(ret1, ret2);
}
int main() {
  memset(dp, -1, sizeof(dp));
  scanf("%s", s + 1);
  n = strlen(s + 1);
  dfs(1, 0);
  if (dp[1][0] == n) {
    for (int i = 1; i <= n; i++) {
      if (s[i] == '0') {
        printf("0");
        return 0;
      }
    }
    printf("-1");
    return 0;
  }
  int mod = 0;
  for (int i = 1; i <= n; i++) {
    if (dp[i][mod] != dp[i + 1][mod] + 1) {
      printf("%c", s[i]);
      mod = (mod + s[i] - '0') % 3;
    }
  }
}
