def bitByBit(input1, input2):
    n, a = input1, input2
    o = set()
    for i in range(n):
        c = 0
        for j in range(i, n):
            c |= a[j]
            o.add(c)
    m = float('inf')
    l = list(o)
    k = len(l)
    for i in range(k):
        for j in range(i + 1, k):
            m = min(m, l[i] ^ l[j])
    return m if m != float('inf') else 0

#include <bits/stdc++.h>
using namespace std;
int solve(int n) {
    if (n <= 0) return 1;  
    return (1 << (int)(log2(n - 1) + 1));
}
int main() {
    int N;
    cin >> N; 
    vector<int> A(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i]; 
    }
    vector<int> squaredA(N);
    for (int i = 0; i < N; i++) {
        squaredA[i] = A[i] * A[i]; 
    }
    vector<int> setBits(N);
    int minSetBits = INT_MAX;
    int maxSetBits = INT_MIN;
    int X, Y;
    for (int i = 0; i < N; i++) {
    setBits[i] = __builtin_popcount(squaredA[i]);  
    if (setBits[i] < minSetBits) {
    minSetBits = setBits[i];
    Y = squaredA[i];  
    }
    if (setBits[i] > maxSetBits) 
    {
    maxSetBits = setBits[i];
    X = squaredA[i]; 
    }
    }
    int product = X * Y;
    int result = solve(product);
    cout << result << endl;
    return 0;
}