import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Xinyi Tao
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1SwapABC135 solver = new B0Or1SwapABC135();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1SwapABC135 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1SwapABC135 solver = new B0Or1SwapABC135();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1SwapABC135 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1SwapABC135 solver = new B0Or1SwapABC135();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1SwapABC135 solver = new B0Or1SwapABC135();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) B0Or1SwapABC135 solver = new B0Or1SwapABC135(); solver new B0Or1SwapABC135() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class B0Or1SwapABC135 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        }

    } B0Or1SwapABC135 public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        } solve {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        } int n = in.nextInt(); n in.nextInt() in.nextInt in int c = 0; c 0 for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            } int i = 1; int i = 1; i 1 i <= n i n i++ i++ i {
                if (in.nextInt() == i) c++;
            } {
                if (in.nextInt() == i) c++;
            } if (in.nextInt() == i) c++; in.nextInt() == i in.nextInt() in.nextInt in i c++ c out.println(c == n || c + 2 == n ? "YES" : "NO") out.println out c == n || c + 2 == n ? "YES" : "NO" c == n || c + 2 == n c == n c n c + 2 == n c + 2 c 2 n "YES" "NO" int testNumber testNumber Scanner in in PrintWriter out out public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1SwapABC135 solver = new B0Or1SwapABC135();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1SwapABC135 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1SwapABC135 solver = new B0Or1SwapABC135();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1SwapABC135 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Xinyi Tao
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1SwapABC135 solver = new B0Or1SwapABC135();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1SwapABC135 {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int c = 0;
            for (int i = 1; i <= n; i++) {
                if (in.nextInt() == i) c++;
            }
            out.println(c == n || c + 2 == n ? "YES" : "NO");

        }

    }
}

