#include <bits/stdc++.h>

using namespace std;


int main(){
    int n;
    cin >> n;
    vector<int> calories(n);
    for(int calories_i = 0; calories_i < n; calories_i++){
       cin >> calories[calories_i];
    }
       
    int len = n * (n - 1);
    int result = 0;
    for (int x = 0; x < n; x++) {
        for (int y = 0; y < n; y++) {
            int h = 0;
            int pw = 0;
            h = 0 + (calories[x] * pow(2, pw)); 
            pw++;
             // cout << "X "<< x <<": " << calories[x] << "\t" << h << " Nilai H " << "\n";
            if (calories[x] != calories[y]) {
                h = h + (calories[y] * pow(2, pw)); 
                // cout << "Y "<< y <<": " << calories[y] << "\t" << h << " Nilai H " << "\n";
                pw++;
                for (int b = 0; b < n; b++) {
                    if (calories[b] != calories[y] && calories[b] != calories[x]) {
                        h = h + (calories[b] * pow(2, pw));
                        // cout << "B "<< b <<": " << calories[b] << "\t" << h << " Nilai H " << "\n";
                    }
                    pw++;
                }
                // cout << "Nilai H : " << h << "\n";
                if (result == 0) {
                    result = h;
                }

                if (result > h && h != 0) {
                    result = h;
                }
            }    
        }
    }
    // your code goes here
    cout << result;
    return 0;
}