Case 1: 16 shrinks to 4 in 7 step(s).

Case 2: 1 shrinks to 1 in 0 step(s).

Case 3: 12345 shrinks to 4 in 10 step(s).

Case 4: 5796 shrinks to 4 in 9 step(s).

Case 5: 3812956 shrinks to 4 in 11 step(s).

Case 6: 68 shrinks to 1 in 2 step(s).

Case 7: 86 shrinks to 1 in 2 step(s).

Case 8: 96 shrinks to 4 in 12 step(s).

Case 9: 4 shrinks to 4 in 0 step(s).