10610 30

#include <stdio.h>
#include <string.h>
 
char arr[100001] = { 0 };
int num[100001];
 
void qSort(int left, int right) {
    int l = left + 1, r = right, pivot = num[left];
 
    do {
        while (num[l] <= pivot && l < right) l++;
        while (pivot <= num[r] && left < r) r--;
 
        if (l < r) {
            int temp = num[l];
            num[l] = num[r];
            num[r] = temp;
        }
    } while (l < r);
 
    int temp = num[left];
    num[left] = num[r];
    num[r] = temp;
 
    if (left < r - 1) qSort(left, r - 1);
    if (r + 1 < right) qSort(r + 1, right);
}
 
int main() {
    scanf("%s", arr);
    int len = strlen(arr);
 
    for (int i = 0; i < len; i++) {
        num[i] = (int)arr[i]-48;
    }
 
    qSort(0, len - 1);
 
    int numSum = 0, flag = 0;
    for (int i = 0; i < len; i++) {
        numSum += num[i];
        if (num[i] == 0)
            flag = 1;        
    }
 
    if (numSum % 3 != 0 || flag==0) {
        printf("-1");
        return 0;
    }
 
    for (int i = len - 1; i >= 0; i--) {
        printf("%d", num[i]);
    }
}