#include <iostream>

#define REP(i,s,n) for(int i=(int)(s);i<(int)(n);i++)

using namespace std;
typedef long long int ll;


int a[51];
int main(void){
  int n;
  cin >> n;
  int c = 0;
  REP(i, 0, n) {
    cin >> a[i];
  }
  REP(i, 0, n) {
    REP(j, i + 1, n) {
      c += a[i] > a[j] ? 1 : 0;
    }
  }
  cout << (c % 2 ? "No" : "Yes") << endl;
}