20pts

#include<bits/stdc++.h>
using namespace std;
struct ple{
    int tongzhuo;
}a[5001];
main(){
	int n,b=1;
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>a[i].tongzhuo;
    for(int i=1;i<=n;i+=2){
        if(a[a[i].tongzhuo].tongzhuo!=i||a[i].tongzhuo==i)
            b=0;
    }
    if(b)
        cout<<"Yes";
    else
        cout<<"No";
}