#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define endl '\n' #define ALL(v) (v).begin(), (v).end() #define RALL(v) (v).rbegin(), (v).rend() #define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end()) typedef long long ll; typedef long double ld; typedef pair P; typedef complex comp; typedef vector< vector > matrix; struct pairhash { public: template size_t operator()(const pair &x) const { size_t seed = hash()(x.first); return hash()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2); } }; const int inf = 1e9 + 9; const ll mod = 1e9 + 7; const double eps = 1e-8; const double pi = acos(-1); int n; int a[60]; int b[60]; bool solve() { for (int i = 0; i < n; i++) { b[a[i]] = i+1; } int c[n+1]; bool used[n+1]; memset(c, 0, sizeof(c)); memset(used, false, sizeof(used)); for (int i = 1; i <= n; i++) { if (!used[i]) { int cnt = 1, v = b[i]; used[i] = true; while (v != i) { used[v] = true; v = b[v]; cnt++; } c[cnt]++; } } for (int i = 2; i <= n; i+=2) { if (c[i]%2) return false; } return true; } void input() { cin >> n; for (int i = 0; i < n; i++) cin >> a[i]; } int main() { ios::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(15); input(); cout << (solve()?"Yes":"No") << endl; }