#include <iostream>
#include <vector>

using namespace std;
#define int long long

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    int a;
    cin >> a;
    int cur = 0;
    string s = "";
    int lposIndex = a-1;
    vector<int> curs;
    for (size_t i = 0; i < a; i++)
    {
        curs.push_back(cur);
        cur/=10;
        int b;
        cin >> b;
        cur+=b;
        //cout << cur << "\n";
    }
    int tV = 1;
    if(cur==0) {
        for (size_t i = 0; i < curs.size(); i++)
        {
            if(curs[i]!=0) {
                lposIndex = i-1;
                cur = curs[i];
            }
        }
        if(lposIndex==(a-1)) {
            cout << 0 << "\n";
            return 0;
        }
        
    }
    for (size_t i = 0; i < 18; i++)
    {
        tV*=10;
        if(tV>=cur) {
            cur=cur-(cur%(tV/10));
            break;
        }
        if(i==17 && tV<=cur) {
            cur = cur-(cur%1000000000000000000);
        }
    }
    for (size_t i = 0; i < lposIndex; i++)
    {
        s+='0';
    }
    cout << cur << s << "\n";
}