#include <bits/stdc++.h>
using namespace std;
void solve(long long n, std::vector<long long> x) {
  int cnt = 0;
  int m = n - 1;
  for (int j = 0; j < n; ++j) {
    if (1 == j + 1) continue;
    for (int i = 0; i < j; ++i) {
      cnt = cnt * 2 - (cnt + 1) * cnt;
    }
  }
  cout << cnt << endl;
}
signed main() {
  long long N;
  scanf("%lld", &N);
  std::vector<long long> x(N);
  for (int i = 0; i < N; i++) {
    scanf("%lld", &x[i]);
  }
  solve(N, x);
  return 0;
}
