#include <bits/stdc++.h>
using namespace std;
string s;
int main(){
    cin >> s;
    int n = s.size();
    s = " " + s;
    if(s[1] == '0' || s[n] == '1')return cout << -1 << endl, 0;
    for(int i = 1; i < n; i++){
        if(s[i] != s[n - i])
            return cout << -1 << endl, 0;
    }

    int cur = 1;
    for(int i = 2; i <= n; i++){
        cout << cur << " " << i << endl;
        if(s[i - 1] == '1'){
            cur = i;
        }
    }
}

### 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 <bits/stdc++.h>
using namespace std;
string s;
int main(){
    cin >> s;
    int n = s.size();
    s = " " + s;
    if(s[1] == '0' || s[n] == '1')return cout << -1 << endl, 0;
    for(int i = 1; i < n; i++){
        if(s[i] != s[n - i])
            return cout << -1 << endl, 0;
    }

    int cur = 1;
    for(int i = 2; i <= n; i++){
        cout << cur << " " << i << endl;
        if(s[i - 1] == '1'){
            cur = i;
        }
    }
}

```