#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int main(){
    int N; cin >> N;
    vi A(N), B(N), C(N+1);
    rep(i, N)cin >> A[i], --A[i];
    rep(i, N){
        if(B[i])continue;
        int k = i, c = 0;
        do{
            c++;
            k = A[k];
            B[k] = 1;
        } while(k != i);
        C[c]++;
    }
    int x = 1;
    rep(i, N + 1)if(!(i & 1) && C[i] & 1)x = 0;
    puts(x ? "YES" : "NO");
}