#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=1e5+10;
char s[N];
int n,rt;
bool firstcheck(){
	if (s[1]=='0'||s[n]=='1') return false;
	for (int i=1;i<n;++i)
		if (s[i]!=s[n-i]) return false;
	return true;
}

int main(){
#ifndef ONLINE_JUDGE
	//freopen("a.in","r",stdin);
#endif
	scanf("%s",s+1);
	n=strlen(s+1);
	if (!firstcheck()){printf("-1\n"); return 0;}
	rt=1;
	for (int i=1;i<n;++i){
		printf("%d %d\n",rt,i+1);
		if (s[i]=='1') rt=i+1;
	}
}

### Prompt

Please create a solution in CPP to the following problem:

You are given a string s of length n. Does a tree with n vertices that satisfies the following conditions exist?

* The vertices are numbered 1,2,..., n.
* The edges are numbered 1,2,..., n-1, and Edge i connects Vertex u_i and v_i.
* If the i-th character in s is `1`, we can have a connected component of size i by removing one edge from the tree.
* If the i-th character in s is `0`, we cannot have a connected component of size i by removing any one edge from the tree.



If such a tree exists, construct one such tree.

Constraints

* 2 \leq n \leq 10^5
* s is a string of length n consisting of `0` and `1`.

Input

Input is given from Standard Input in the following format:


s


Output

If a tree with n vertices that satisfies the conditions does not exist, print `-1`.

If a tree with n vertices that satisfies the conditions exist, print n-1 lines. The i-th line should contain u_i and v_i with a space in between. If there are multiple trees that satisfy the conditions, any such tree will be accepted.

Examples

Input

1111


Output

-1


Input

1110


Output

1 2
2 3
3 4


Input

1010


Output

1 2
1 3
1 4

### Response

```cpp
#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=1e5+10;
char s[N];
int n,rt;
bool firstcheck(){
	if (s[1]=='0'||s[n]=='1') return false;
	for (int i=1;i<n;++i)
		if (s[i]!=s[n-i]) return false;
	return true;
}

int main(){
#ifndef ONLINE_JUDGE
	//freopen("a.in","r",stdin);
#endif
	scanf("%s",s+1);
	n=strlen(s+1);
	if (!firstcheck()){printf("-1\n"); return 0;}
	rt=1;
	for (int i=1;i<n;++i){
		printf("%d %d\n",rt,i+1);
		if (s[i]=='1') rt=i+1;
	}
}

```