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A.cpp
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A.cpp
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#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define ff first
#define ss second
#define rep(i, n) for(int i = 0; i < n; ++i)
#define repR(i, n) for (int i = n-1; i >= 0; --i)
#define repA(i, a, n) for (int i = a; i <= n; ++i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()
#define mem1(a) memset(a,-1,sizeof(a))
#define mem0(a) memset(a,0,sizeof(a))
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
#define vi vector<int>
#define vvi vector<vi>
#define vll vector<ll>
#define vvll vector<vll>
#define vs vector<string>
#define vd vector<double>
#define vb vector<bool>
#define vpii vector<pii>
#define vpll vector<pll>
#define vpdd vector<pdd>
#define mod 1000000007
#define ps(x,y) fixed << setprecision(y) << x
#define fastio ios_base::sync_with_stdio(false),cin.tie(NULL),cout.tie(NULL)
ll dp[61];
void solve()
{
ll n;
cin >> n;
if (n % 2 == 1) {
cout << 0 << '\n';
return;
}
dp[0] = dp[1] = 0;
dp[2] = 2;
for (int i = 4; i <= n; i += 2) {
dp[i] = 2 * dp[i - 2];
}
cout << dp[n] << '\n';
}
int main()
{
fastio;
/*#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif*/
int t = 1;
//cin >> t;
while (t--) solve();
return 0;
}