Determine the positions of each letter in a given string (with length < 1000001). Then output the positions of each letters in lexicographical order. For each letter, output its positions in increasing order.
For example, “AbAABBCAaa”
A is at position 0, 2, 3, 7; B is at position 4, 5; C is at position 6; a is at position 8, 9; b is at position 1.
There is only one row, and it is a string S with length smaller than 1000001.
Please output the answer according to the above requirements, and remember to add ‘\n’ at the end of the outcome of every letter.