#include<bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin >> s;
    int n = s.size();
    s = '0' + s;
    for(int i = 0; i <= n; i++){
        if(s[i] != s[n - i]){
            cout << "-1"<<endl;
            return 0;
        }
    }
    if(s[1] == '0'){
        cout<<"-1"<<endl;
        return 0;
    }
    int rt = 1;
    int cnt = 2;
    for(int i = 1; i < n; i++){
        cout <<rt <<" "<<cnt<<endl;
        if(s[i] == '1') rt = cnt;
        cnt ++;
    }

}

### 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<bits/stdc++.h>
using namespace std;
int main(){
    string s;
    cin >> s;
    int n = s.size();
    s = '0' + s;
    for(int i = 0; i <= n; i++){
        if(s[i] != s[n - i]){
            cout << "-1"<<endl;
            return 0;
        }
    }
    if(s[1] == '0'){
        cout<<"-1"<<endl;
        return 0;
    }
    int rt = 1;
    int cnt = 2;
    for(int i = 1; i < n; i++){
        cout <<rt <<" "<<cnt<<endl;
        if(s[i] == '1') rt = cnt;
        cnt ++;
    }

}

```