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

int main(){
  string s;
  cin >> s;
  int n=s.size();
  if(s[0] == '0' || s[n-1]  == '1'){
    cout << -1<< endl;
    return 0;
  }
  s = s.substr(0, n-1);
  string t = s;
  reverse(t.begin(), t.end());
  if (s!=t){
    cout<<-1<<endl;
    return 0;
  }
  s=s+"1";
  vector<int> p(n, -1);
  for (int i = 1; i<n; ++i){
    if(s[i] != '1'){
      continue;
    }
    for(int j=i-1;j>=0 &&p[j] < 0; --j){
      p[j]=i;
      cout<<i+1<<" "<<j+1<<endl;
    }
  }
  return 0;
}

### 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 main(){
  string s;
  cin >> s;
  int n=s.size();
  if(s[0] == '0' || s[n-1]  == '1'){
    cout << -1<< endl;
    return 0;
  }
  s = s.substr(0, n-1);
  string t = s;
  reverse(t.begin(), t.end());
  if (s!=t){
    cout<<-1<<endl;
    return 0;
  }
  s=s+"1";
  vector<int> p(n, -1);
  for (int i = 1; i<n; ++i){
    if(s[i] != '1'){
      continue;
    }
    for(int j=i-1;j>=0 &&p[j] < 0; --j){
      p[j]=i;
      cout<<i+1<<" "<<j+1<<endl;
    }
  }
  return 0;
}

```