Let `A` be the set of all 50 students of class `X I I` in a central school. Let `f: A->N` be a function defined by `f(x)="Roll number of student x"` Show that `f` is one-one but not onto.

Explanation

`f(x) ="Roll number of students x"`


`"One one" `


`f(x_1)="roll number of students " x_1`


`f(x_2)="roll number of students " x_2`


...