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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;

#define F first
#define S second
const long long mod = 1000000007;

int N, A[100], X, K;

int main() {
    //freopen("input.in","r",stdin);
    cin >> N;
    int maxi = 1, mini = 1;
    for(int i = 1;i <= N;i++) {
        cin >> A[i];
        if(A[i] > A[maxi]) maxi  = i;
        if(A[i] < A[mini]) mini  = i;
    }

    vector<pair<int, int> > ans;
    if(A[maxi] >= 0 and A[mini] < 0) {        
        if(A[maxi]+A[mini] >= 0) {
            for(int i = 1;i <= N;i++) {
                ans.push_back({maxi, i});
            }
        } else {
            for(int i = 1;i <= N;i++) {
                ans.push_back({mini, i});
            }
        }
    }

    maxi = mini = 1;
    for(auto t : ans) {
        A[t.S] += t.F;
    }
    for(int i = 1;i <= N;i++) {     
        if(A[i] > A[maxi]) maxi  = i;
        if(A[i] < A[mini]) mini  = i;
    }

    if(A[maxi] >= 0 and A[mini] >= 0) {        
        for(int i = 2;i <= N;i++) {
            ans.push_back({i-1, i});
        }        
    } else {
        for(int i = N-1;i >= 1;i--) {
            ans.push_back({i+1, i});
        }        
    }

    cout << ans.size() << endl;
    for(auto t : ans) {
        cout << t.F << " " << t.S << endl;
    }

    return 0;
}