this shit aint working

// Problem: B. Hometask
// Contest: Codeforces - Codeforces Round #131 (Div. 2)
// Memory Limit: 256 MB
// Time Limit: 2000 ms
// Date / Time: 2021-08-16 09:24:28
// Author: cosenza
// всё что ни делается - всё к лучшему
// check list -> long long, special cases, array size, mod (a*b%p*c%p not a*b*c%p  ,  (a-b+p)%p not a-b )
//
// Powered by CP Editor (https://cpeditor.org)

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    multiset<int> ms;
    int cnt0 = 0, r1 = 0, r2 = 0;
    for(int i = 0; i < n; i++) {
        int k;
        cin >> k;
        ms.insert(k);
        if(k == 0) {
            cnt0++;
        }
        if(k % 3 == 1) {
            r1++;
        } else if(k % 3 == 2) {
            r2++;
        }
    }
    int tot = accumulate(ms.begin(), ms.end(), 0);
    if(!cnt0) {
        cout << "-1\n";
        return 0;
    }
    if(tot % 3 == 1) {
        if(r1) {
            for(auto k : ms) {
                if(k % 3 == 1) {
                    ms.erase(ms.find(k));
                    break;
                }
            }
        } else if(r2) {
            int cnt = 0;
            for(auto k : ms) {
                if(k % 3 == 2 and cnt < 2) {
                    ms.erase(ms.find(k));
                    cnt++;
                }
                if(cnt == 2) {
                    break;
                }
            }
        } else {
            cout << "-1\n";
            return 0;
        }
    } else if(tot % 3 == 2) {
        if(r2) {
            for(auto k : ms) {
                if(k % 3 == 2) {
                    ms.erase(ms.find(k));
                    break;
                }
            }
        } else if(r1) {
            int cnt = 0;
            for(auto k : ms) {
                if(k % 3 == 1 and cnt < 2) {
                    ms.erase(ms.find(k));
                    cnt++;
                }
                if(cnt == 2) {
                    break;
                }
            }
        } else {
            cout << "-1\n";
            return 0;
        }
    }
    vector<int> v(ms.begin(), ms.end());
    reverse(v.begin(), v.end());
    for(auto k : v) {
        cout << k;
    }
    cout << "\n";
    return 0;
}