Fill each row, column, and box with the digits 0-6 once each. Exactly one cell in each row, column, and box is a "Schrödinger's cell," which contains two digits. Two Schrödinger's cells cannot contain the same pair of digits. A cell's value is equal to the sum of its digits. For final solution check purposes, if a cell's value is from 0-9, enter the digit equal to its value; otherwise, the cell may be left empty (in-progress solution-checking doesn't work properly in this puzzle). Cells with red squares are index cells. If an index cell in column X has a value of Y, then the cell in column Y in the same row has a value of X (e.g. if r3c1 has a value of 5, then r3c5 has a value of 1). An index cell may contain two digits, but may not have a value greater than 6. If an index cell has a value of zero, the value being indexed does not appear in the row. Nothing in these rules prevents a value from repeating in a row, even if one instance of that value is referenced by an index cell. The sum of the values along an arrow is equal to the value in the connected circle.