#include<bits/stdc++.h> using namespace std; int main() { string s,s1; bool f=true; int t=0; cin>>s; for (int i=0;i<s.length();i++) { int z=s[i]-'0'; t+=z; if (s[i]=='0'&&f==true) f=false; else s1=s1+s[i]; } if (t%3==0&&f==false) cout<<s1<<0; else cout<<-1; }
