If the number of decompositions is infinite, print −1 on the first line and nothing else.
Otherwise print the number of decompositions on the first line. Then print one decomposition per line. On each line print the number of elements k of that decomposition first, then the k elements in non-decreasing order, separated by single spaces.
Two different decompositions always have a different number of elements, so print the lines in increasing order of k.