Codeforces Round #359 (Div. 2) B

B. Little Robber Girl's Zoo

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

Little Robber Girl likes to scare animals in her zoo for fun. She decided to arrange the animals in a row in the order of non-decreasing height. However, the animals were so scared that they couldn't stay in the right places.

The robber girl was angry at first, but then she decided to arrange the animals herself. She repeatedly names numbers l and r such that r - l + 1 is even. After that animals that occupy positions between l and r inclusively are rearranged as follows: the animal at position l swaps places with the animal at position l + 1, the animal l + 2 swaps with the animal l + 3, ..., finally, the animal at position r - 1 swaps with the animal r.

Help the robber girl to arrange the animals in the order of non-decreasing height. You should name at most 20 000 segments, since otherwise the robber girl will become bored and will start scaring the animals again.

Input

The first line contains a single integer n (1 ≤ n ≤ 100) — number of animals in the robber girl's zoo.

The second line contains n space-separated integers a₁, a₂, ..., a_n (1 ≤ a_i ≤ 10⁹), where a_i is the height of the animal occupying the i-th place.

Output

Print the sequence of operations that will rearrange the animals by non-decreasing height.

The output should contain several lines, i-th of the lines should contain two space-separated integers l_i and r_i (1 ≤ l_i < r_i ≤ n) — descriptions of segments the robber girl should name. The segments should be described in the order the operations are performed.

The number of operations should not exceed 20 000.

If the animals are arranged correctly from the start, you are allowed to output nothing.

Examples

Input

4
2 1 4 3

Output

1 4

Input

7
36 28 57 39 66 69 68

Output

1 4
6 7

Input

5
1 2 1 2 1

Output

2 5
3 4
1 4
1 4

Note

Note that you don't have to minimize the number of operations. Any solution that performs at most 20 000 operations is allowed

题意：给你一段序列  一种 操作 在【l,r】区间上（l-r+1为偶数）swap（l，l+1），swap（l+2，l+3）.....

最终使得序列为非递减序列  输出操作流程

题解；不要求操作步骤最少，所以可以考虑区间长度都为2的操作  找到最小的值不断交换向前移动

 #include<bits/stdc++.h>
 #include<iostream>
 #include<cstring>
 #include<cstdio>
 #include<algorithm>
 #define ll __int64
 #define pi acos(-1.0)
 using namespace std;
 ll n;
 ll a[];
 ll minx;
 ll minpos;
 int main()
 {
     scanf("%I64d",&n);
     for(int i=;i<=n;i++)
     {
         scanf("%I64d",&a[i]);
     }
     for(int i=;i<=n;i++)
     {
         minx=;
         minpos=;
         for(int j=i;j<=n;j++)
         {
             if(a[j]<minx)
               {
                   minx=a[j];
                   minpos=j;
               }
         }
         for(int k=minpos;k>=i+;k--)
         {
             swap(a[k],a[k-]);
             printf("%d %d\n",k-,k);
         }
     }
     return ;
 }