import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Jaynil
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1Swap solver = new B0Or1Swap();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1Swap {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}
 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.StringTokenizer; StringTokenizer java.util import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.InputStream; InputStream java.io public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1Swap solver = new B0Or1Swap();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1Swap {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1Swap solver = new B0Or1Swap();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1Swap solver = new B0Or1Swap();
        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 InputReader in = new InputReader(inputStream); in new InputReader(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) B0Or1Swap solver = new B0Or1Swap(); solver new B0Or1Swap() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class B0Or1Swap {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        }

    } B0Or1Swap public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        } solve {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        } int n = in.nextInt(); n in.nextInt() in.nextInt in int a[] = new int[n + 1]; a new int[n + 1] n + 1 n 1 int count = 0; count 0 for (int i = 1; i <= n; i++) a[i] = in.nextInt(); int i = 1; int i = 1; i 1 i <= n i n i++ i++ i a[i] = in.nextInt(); a[i] = in.nextInt() a[i] a i in.nextInt() in.nextInt in for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            } int i = 1; int i = 1; i 1 i <= n i n i++ i++ i {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            } {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            } if (a[i] == i) {
                    continue;
                } a[i] == i a[i] a i i {
                    continue;
                } continue; if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                } a[a[i]] == i a[a[i]] a a[i] a i i {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                } count++ count int temp = a[i]; temp a[i] a i a[i] = i a[i] a i i a[temp] = temp a[temp] a temp temp continue; out.println("NO") out.println out "NO" return; if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            } count <= 1 count 1 out.println("YES") out.println out "YES" {
                out.println("NO");
            } out.println("NO") out.println out "NO" int testNumber testNumber InputReader in in PrintWriter out out static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1Swap solver = new B0Or1Swap();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1Swap {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1Swap solver = new B0Or1Swap();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1Swap {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author Jaynil
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B0Or1Swap solver = new B0Or1Swap();
        solver.solve(1, in, out);
        out.close();
    }

    static class B0Or1Swap {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            int n = in.nextInt();
            int a[] = new int[n + 1];
            int count = 0;
            for (int i = 1; i <= n; i++) a[i] = in.nextInt();
            for (int i = 1; i <= n; i++) {
                if (a[i] == i) {
                    continue;
                }
                if (a[a[i]] == i) {
                    count++;
                    int temp = a[i];
                    a[i] = i;
                    a[temp] = temp;
                    continue;
                }
                out.println("NO");
                return;
            }
            if (count <= 1)
                out.println("YES");
            else {
                out.println("NO");
            }
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}

