7 9 1 1 1 -1 -1 -1 0 0 0 1 1 1 0 0 0 -1 -1 -1 0 1 1 -1 0 0 -1 0 0 1 0 1 0 -1 0 0 -1 0 1 1 0 0 0 -1 0 0 -1 0 1 1 0 -1 0 0 0 -1 1 1 0 0 -1 0 -1 0 0 equations 4 10 1 0 0 0 0 0 0 0 0 2 0 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 1 0 0 2 0 0 0 0 0 0 0 0 1 2 congruences 1 9 1 1 1 0 0 0 0 0 0 grading