#include <bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef set<int> si;
const int inf = 1e9;
const int mod = 1e9+7;

int n, a[51];
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> n;
  FOR(i, 1, n+1){
    cin >> a[i];
  }
  int count = 0;
  FOR(i, 0, n){
    FOR(j, 1, n){
      if(a[j] > a[j+1]){
        swap(a[j], a[j+1]);
        count++;
      }
    }
  }
  cout << (count&1 ? "No" : "Yes") << endl;
}