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

int n, u;
string s;

signed main () {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
    cin >> s;
    n = s.size();
    if (s.front() == '0' || s.back() == '1')
		cout << "-1\n";
	else {
		for (int i = 0; i < n / 2; ++i) {
			if (s[i] != s[n - i - 2])  {
				cout << "-1\n";
				return 0;
			}
		}
		cout << 1 << ' ' << 2 << '\n';
		for (int i = 1; i < n - 1; i++) {
			cout << u + 1 << ' ' << i + 2 << '\n';
			if (s[i] == '1') 
				u = i + 1;
		}
	}
}

### Prompt

Create a solution in cpp for 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 <bits/stdc++.h>
using namespace std;

int n, u;
string s;

signed main () {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
    cin >> s;
    n = s.size();
    if (s.front() == '0' || s.back() == '1')
		cout << "-1\n";
	else {
		for (int i = 0; i < n / 2; ++i) {
			if (s[i] != s[n - i - 2])  {
				cout << "-1\n";
				return 0;
			}
		}
		cout << 1 << ' ' << 2 << '\n';
		for (int i = 1; i < n - 1; i++) {
			cout << u + 1 << ' ' << i + 2 << '\n';
			if (s[i] == '1') 
				u = i + 1;
		}
	}
}

```