#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;   }   