#include<cstdio>
#include<cstring>
using namespace std;
int len;
char n[100010];
int main() {
	scanf("%s",n+1);
	len=strlen(n+1);
	if ((n[len]=='1') || (n[1]=='0')) {
		printf("-1\n");return 0;	
	}
	for (int i=1; i<=len/2+1; i++) 
		if (n[i]!=n[len-i]) {
			printf("-1\n");return 0;
		}
	int root=1;
	for (int i=2; i<=len; i++) {
		printf("%d %d\n",root,i);
		if (n[i-1]=='1') root=i;
	}
	return 0;
} 
### Prompt

Your challenge is to write a CPP solution 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<cstdio>
#include<cstring>
using namespace std;
int len;
char n[100010];
int main() {
	scanf("%s",n+1);
	len=strlen(n+1);
	if ((n[len]=='1') || (n[1]=='0')) {
		printf("-1\n");return 0;	
	}
	for (int i=1; i<=len/2+1; i++) 
		if (n[i]!=n[len-i]) {
			printf("-1\n");return 0;
		}
	int root=1;
	for (int i=2; i<=len; i++) {
		printf("%d %d\n",root,i);
		if (n[i-1]=='1') root=i;
	}
	return 0;
} 
```