#include <bits/stdc++.h>
template <typename T>
void scan(T &x) {
  x = 0;
  bool _ = 0;
  T c = getchar();
  _ = c == 45;
  c = _ ? getchar() : c;
  while (c < 48 || c > 57) c = getchar();
  for (; c < 48 || c > 57; c = getchar())
    ;
  for (; c > 47 && c < 58; c = getchar()) x = (x << 3) + (x << 1) + (c & 15);
  x = _ ? -x : x;
}
template <typename T>
void printn(T n) {
  bool _ = 0;
  _ = n < 0;
  n = _ ? -n : n;
  char snum[65];
  int i = 0;
  do {
    snum[i++] = n % 10 + 48;
    n /= 10;
  } while (n);
  --i;
  if (_) putchar(45);
  while (i >= 0) putchar(snum[i--]);
}
template <typename First, typename... Ints>
void scan(First &arg, Ints &...rest) {
  scan(arg);
  scan(rest...);
}
template <typename T>
void print(T n) {
  printn(n);
  putchar(10);
}
template <typename First, typename... Ints>
void print(First arg, Ints... rest) {
  printn(arg);
  putchar(32);
  print(rest...);
}
using namespace std;
using ll = long long;
const int MM = 505;
int n;
ll a[MM], ans;
int main() {
  scan(n);
  for (int i = 0; i < n; i++) {
    scan(a[i]);
  }
  for (int i = 0; i < n; i++) {
    for (int j = 0; j <= i; j++) {
      for (int k = 0; k <= j; k++) {
        ans = max(ans, a[i] | a[j] | a[k]);
      }
    }
  }
  print(ans);
}
