package chelper;

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import io.InputReader;
import io.OutputWriter;

public class TaskK {
  public void solve(int testNumber, InputReader in, OutputWriter out) {
    int n = in.nextInt();
    int[] a = new int[n];
    int[] b = new int[n];
    for (int i = 0; i < n; i++) {
      a[i] = in.nextInt() - 1;
    }
    for (int i = 0; i < n; i++) {
      b[i] = in.nextInt() - 1;
    }
    int[][] position = new int[2][n];
    Arrays.fill(position[0], -1);
    for (int i = 0; i < n; i++) {
      int x = a[i];
      if (position[0][x] == -1) {
        position[0][x] = i;
      } else {
        position[1][x] = i;
      }
    }
    for (int i = 0; i < n; i++) {
      int x = b[i];
      if (position[0][x] == -1) {
        position[0][x] = i + n;
      } else {
        position[1][x] = i + n;
      }
    }
    List<String> answer = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      if (a[i] == b[i]) {
        continue;
      }
      int x = a[i];
      int pos = position[0][x] == i ? position[1][x] : position[0][x];
      if (pos < n) {
        answer.add((pos + 1) + " " + (i + 1));
        int c = b[i];
        a[pos] = c;
        b[i] = x;
        if (position[0][x] == i) {
          position[1][x] = i + n;
        } else {
          position[0][x] = i + n;
        }
        if (position[0][c] == i + n) {
          position[0][c] = pos;
        } else {
          position[1][c] = pos;
        }
      } else {
        pos -= n;
        answer.add((pos + 1) + " " + (pos + 1));
        answer.add((pos + 1) + " " + (i + 1));
        int c = b[i];
        int d = a[pos];
        int posx1 = i;
        int posc = i + n;
        int posd = pos;
        int posx2 = pos + n;
        a[pos] = c;
        b[i] = x;
        b[pos] = d;
        if (position[0][x] == posx1) {
          position[1][x] = posc;
        } else {
          position[0][x] = posc;
        }
        if (position[0][c] == posc) {
          position[0][c] = posd;
        } else {
          position[1][c] = posd;
        }
        if (position[0][d] == posd) {
          position[0][d] = posx2;
        } else {
          position[1][d] = posx2;
        }
      }
    }
    out.println(answer.size());
    for (String s : answer) {
      out.println(s);
    }
  }
}