#include<cstdio>
#include<cstring>
#include<algorithm>
const int maxn=1e5+10;
int n;
char s[maxn];
void judge()
{
    if(s[1]=='0' || s[n]=='1')
    {
        printf("-1\n");
        return;
    }
    for(int i=1;i<=n;i++)
    {
        if(s[i]=='1' && s[n-i]=='0')
        {
            printf("-1\n");
            return;
        }
    }
    int root=1;
    for(int i=2;i<=n;i++)
    {
        printf("%d %d\n",root,i);
        if(s[i-1]=='1') root=i;
    }
}
int main()
{
    scanf("%s",s+1);
    n=strlen(s+1);
    judge();
}

### Prompt

Generate 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>
#include<algorithm>
const int maxn=1e5+10;
int n;
char s[maxn];
void judge()
{
    if(s[1]=='0' || s[n]=='1')
    {
        printf("-1\n");
        return;
    }
    for(int i=1;i<=n;i++)
    {
        if(s[i]=='1' && s[n-i]=='0')
        {
            printf("-1\n");
            return;
        }
    }
    int root=1;
    for(int i=2;i<=n;i++)
    {
        printf("%d %d\n",root,i);
        if(s[i-1]=='1') root=i;
    }
}
int main()
{
    scanf("%s",s+1);
    n=strlen(s+1);
    judge();
}

```