#include <bits/stdc++.h>
#define ll long long
using namespace std;



int main() {


    ll n;
    cin >> n;
    vector<ll> seq(n);
    for (int i = 0; i < n; i++) cin >> seq[i];

    vector<bool> used(n, false);
    vector<vector<ll>> circles;
    ll k;
    for (int i = 0; i < n; i++) {
        if (used[i]) continue;
        if (seq[i] == i) continue;
        circles.push_back({i});
        k = seq[i];
        while (k != i) {
            used[k] = true;
            circles.back().push_back(k);
            k = seq[k];
        }
    }
    for (auto &c: circles) {
        sort(c.begin(), c.end());
        for (int i = 0; i < c.size() - 1; i++) {
            if (seq[c[i]] < seq[c[i+1]]) {
                cout << "NO" << endl;
                return 0;
            }
        }
    }
    cout << "YES" << endl;

    vector<pair<ll, ll>> ps;
    for (auto &c: circles) {
        ps.push_back({c[0], c[1]});
    }

    sort(ps.begin(), ps.end());
    set<ll> u;
    for (auto [a, b]: ps) {
        if (u.empty() || *(--u.end()) < b) {
            u.insert(b);
        } else {
            auto it = u.lower_bound(b);
            u.erase(it);
            u.insert(b);
        }
    }
    cout << u.size() << endl;




    return 0;
}