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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include<deque>
#include<queue>
#include<vector>
#include<algorithm>
#include<iostream>
#include<set>
#include<cmath>
#include<tuple>
#include<string>
#include<chrono>
#include<functional>
#include<iterator>
#include<random>
#include<unordered_set>
#include<unordered_map>
#include<array>
#include<map>
#include<bitset>
#include<iomanip>
using namespace std;
typedef long long int llint;
typedef long double lldo;
#define mp make_pair
#define mt make_tuple
#define pub push_back
#define puf push_front
#define pob pop_back
#define pof pop_front
#define fir first
#define sec second
#define res resize
#define ins insert
#define era erase
//ios::sync_with_stdio(false);
//std::cin.tie(0);
//<< setprecision(20)
const int mod=1e9+7;
const llint big=1e15+100;
const long double pai=3.141592653589793238462643383279502884197;
const long double ena=2.71828182845904523536;
const long double eps=1e-7;
template <class T,class U>void mineq(T& a,U b){if(a>b){a=b;}}
template <class T,class U>void maxeq(T& a,U b){if(a<b){a=b;}}
template <class T> void soun(T& ar)
{sort(ar.begin(),ar.end());ar.erase(unique(ar.begin(),ar.end()),ar.end());}
llint gcd(llint a,llint b){if(a%b==0){return b;}else return gcd(b,a%b);}
llint lcm(llint a,llint b){return a/gcd(a,b)*b;}
int main(void){
	int n,i;cin>>n;
	int uede=-1,ues=0,stde=-1,sts=0;
	for(i=0;i<n;i++){
		int q;cin>>q;
		if(ues<=q){uede=i;ues=q;}
		if(sts>=q){stde=i;sts=q;}
	}
	vector<pair<int,int>>sosa;
	cout<<2*n<<endl;
	if(abs(ues)>abs(sts)){
		cout<<uede<<" 0"<<endl;
		cout<<uede<<" 0"<<endl;
		for(i=0;i<n-1;i++){
			cout<<i<<" "<<i+1<<endl;
			cout<<i<<" "<<i+1<<endl;
		}
	}else{
		cout<<stde<<" "<<n-1<<endl;
		cout<<stde<<" "<<n-1<<endl;
		for(i=n-1;i>0;i--){
			cout<<i<<" "<<i-1<<endl;
			cout<<i<<" "<<i-1<<endl;
		}
	}
	return 0;
}