INPUT ☆☆☆
`INPUT variable_1, variable_2, …, variable_n`
assigns data entered from the keyboard to variables.
When an INPUT statement has two or more variables, the values are written punctuated by commas in the input reply.
The values must be constants, that is, they cannot be expressions.
Example.
On execution of
`INPUT a, b`
enter the data as
`2 , 3`
An input reply for an INPUT statement can consist of two or more lines.
In such a case, any line except the last must be written ending with a comma.
However no item can be written divided into more than one line.
Example. For
`INPUT a, b`
an input reply can be as
`2,
3
`
If an item is assigned to a string variable, the item should be enclosed in the double quotes, otherwise leading or trailing spaces shall be eliminated.
Example.
If
`" Sure ?"`
is entered for
`INPUT s$`
s$ shall be `Sure ?`.
Note.
When an input line whose last character except spaces is a comma, it has a continuation line.
Therefore, the null string cannot be input without quoted.

References.
If you want to input characters without quoted, use LINE INPUT.
Refer to Non-fatal exceptions