Problem:
Score : 700 points

Problem Statement

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.

Sample Input 1

1111

Sample Output 1

-1

It is impossible to have a connected component of size n after removing one edge from a tree with n vertices.

Sample Input 2

1110

Sample Output 2

1 2
2 3
3 4

If Edge 1 or Edge 3 is removed, we will have a connected component of size 1 and another of size 3. If Edge 2 is removed, we will have two connected components, each of size 2.

Sample Input 3

1010

Sample Output 3

1 2
1 3
1 4

Removing any edge will result in a connected component of size 1 and another of size 3.

Solution in Julia (0.5.0) (judge verdict: Wrong Answer)

parseInt(x)=parse(Int,x)
parseMap(x::Array{SubString{String},1})=map(parseInt,x)

function main()
	s = chomp(readline())
	n = length(s)
	if s[1] == '0' || s[n-1] == '0' || s[n] == '1'
		println(-1)
	else
		flg = 0
		k = div(n-1,2)
		for i in 1:k
			if s[i+1] != s[n-1-i]
				flg = 1
				break
			end
		end
		if flg == 1
			println(-1)
		else
			init = n
			for i in 1:n-2
				if s[i] == '0'
					init = i
					break
				end
			end
			if init > k
				for i in 2:init
					println(i-1, " ", i)
				end
				for i in init+1:n
					println(1, " ", i)
				end
			else
				th = s[div(n,2)]=='1'?1:0
				now = 1
				for i in 2:k
					println(now, " ", i+1)
					if s[i] == '1'
						now += 1
					end
				end
				if th == 0
					for i in k+1:n
						println(1, " ", i)
					end
				else
					println(1, " ", k+1)
					for i in k+2:n
						println(k+1, " ", i)
					end
				end
			end
		end
	end
end
main()