#include <sstream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <iostream>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>

#define INF 1000000000

using namespace std;
typedef long long ll;

int a[64];
int b[64];

int main(void) {
    int N;
    cin >> N;
    for (int i = 1; i <= N; i++) {
        cin >> a[i];
        b[a[i]] = i;
    }
    int cross = 0;
    for (int i = 1; i <= N; i++) {
        for (int j = i+1; j <= N; j++) {
            if (b[i] > b[j]) cross++;
        }
    }
//    cout << cross << endl;
    if (cross % 2 == 1) cout << "No" << endl;
    else cout << "Yes" << endl;
    return 0;
}