Problem:
Score : 600 points

Problem Statement

Snuke has an integer sequence, a, of length N. The i-th element of a (1-indexed) is a_{i}.

He can perform the following operation any number of times:

Operation: Choose integers x and y between 1 and N (inclusive), and add a_x to a_y.

He would like to perform this operation between 0 and 2N times (inclusive) so that a satisfies the condition below. Show one such sequence of operations.
It can be proved that such a sequence of operations always exists under the constraints in this problem.

Condition: a_1 \leq a_2 \leq ... \leq a_{N}

Constraints

2 \leq N \leq 50

-10^{6} \leq a_i \leq 10^{6}

All input values are integers.

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_{N}

Output

Let m be the number of operations in your solution. In the first line, print m.
In the i-th of the subsequent m lines, print the numbers x and y chosen in the i-th operation, with a space in between.
The output will be considered correct if m is between 0 and 2N (inclusive) and a satisfies the condition after the m operations.

Sample Input 1

3
-2 5 -1

Sample Output 1

2
2 3
3 3

After the first operation, a = (-2,5,4).

After the second operation, a = (-2,5,8), and the condition is now satisfied.

Sample Input 2

2
-1 -3

Sample Output 2

1
2 1

After the first operation, a = (-4,-3) and the condition is now satisfied.

Sample Input 3

5
0 0 0 0 0

Sample Output 3

0

The condition is satisfied already in the beginning.

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<iostream>
#include<cstdio>
#include <stdio.h>
#include<algorithm>
#include<cstring>
#include <string>
#include<cmath>
#include<cstdlib>
#include<queue>
#include<map>
#include<vector>
#include<bits/stdc++.h>
#include <set>
#define ll   long long
#define IO ios::sync_with_stdio(false);cin.tie();cout.tie(0)
#define inf 0x3f3f3f
#define pi 3.1415926535898
using namespace std;
const int N=2e5+10;
const int mod=1e9+7;

int main()
{
    int n,pos,tem,flag,mx=0;
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>tem;
        if(abs(tem)>mx)
        {
            mx=abs(tem);
            pos=i;
            if(tem>0)
            {
                flag=1;
            }
            else
            {
                flag=0;
            }
        }
    }
    cout<<2*n-2<<endl;
    for(int i=1;i<=n;i++)
    {
        if(i!=pos)
        {
            cout<<pos<<" "<<i<<endl;
        }
    }
    if(flag)
    {
        for(int i=2;i<=n;i++)
        {
            cout<<i-1<<" "<<i<<endl;
        }
    }
    else
    {
        for(int i=n;i>1;i--)
        {
            cout<<i<<" "<<i-1<<endl;
        }
    }
    return 0;
}