Permutation

There is an array A[1..N] containing each integer from 1 to N exactly once. An array B[1..N] is created from A by the following rule.

B[A[A[i]]] = i (1 <= i <= N)

Given B, find an array A that could have produced it. Such an array may not exist. If two or more arrays A are possible, output any one of them.

The first line contains N, the number of elements in B. (1 <= N <= 20,000)

Each of the next N lines contains one value, B[1], ..., B[N], in order.

If a solution exists, print N on the first line. Then print A[1], ..., A[N], one value per line, in order.

If no solution exists, print 0 on the first line.