import java.util.*;


public class Main {
	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		int n = input.nextInt();
		int[] toys = new int[n + 1];
		toys[0] = 0; // 인덱스와 해당값을 같게 해주는 편의를 위해 0삽입
		int count=0;
		ArrayList<String> result=new ArrayList<String>();

		for (int i = 1; n >= i; i++) {
			int toy = input.nextInt();
			toys[i] = toy;
		} // 입력된 장난감 순서 배열 완성

		for (int i = 1; i <= n; i++) { // 총 n번 돌리기( i : 1,2,...,n )
			if (toys[i] != i) {
				int startIndex = i;
				int endIndex = 0;

				for (int j = i + 1; j <= n; j++) {
					if (toys[j] == i) {
						endIndex = j;
					}
				}
//				System.out.println(Arrays.toString(toys));
//				System.out.println("바꿔야할인덱스 : "+startIndex+" "+endIndex);
				count+=1;
				if (count>100) {
					break;
				}
				result.add(Integer.toString(startIndex));
				result.add(Integer.toString(endIndex));
				
				int[] sliceBefore = Arrays.copyOfRange(toys, startIndex, endIndex + 1); // 정렬해야할 부분배열 설정
				int sliceLength = sliceBefore.length;
				int[] sliceAfter = new int[sliceLength];

				for (int j = 0; j < sliceLength; j++) {
					sliceAfter[sliceLength - 1 - j] = sliceBefore[j];
				} // 부분배열 정렬
//				System.out.println(Arrays.toString(sliceBefore));
//				System.out.println(Arrays.toString(sliceAfter));
				
				System.arraycopy(sliceAfter, 0, toys, startIndex, sliceLength);
//				System.out.println(Arrays.toString(toys));

			}
			
		}
//		System.out.println(Arrays.toString(toys));
		
		if(count>100) {
			System.out.println(-1);
		}else {
			System.out.println(count);
			for(int j=0;j<count;j++) {
				System.out.println(result.get(2*j)+" "+result.get(2*j+1));
		}
		
		
			
		}
		
		
		
	}
}