How many functions f:{1,2,3}→{1,2,3,4,5,6}f: \{1, 2, 3\} \to \{1, 2, 3, 4, 5, 6\}f:{1,2,3}→{1,2,3,4,5,6} satisfy the condition f(1)<f(2)f(1) < f(2)f(1)<f(2) and f(2)<f(3)f(2) < f(3)f(2)<f(3)?
20
15
120
216