Write a c$++$ program that takes in a C$-$string as input, and outputs yes if every character in the C$-$string is a digit $0-9.$

The input will contain with a maximum of $6$ characters before the null.

You'll need to include additional header files in your solution.

Ex: If the input is:

$1995$

the output is:

yes

Ex: If the input is:

$42,000$

or

$1995!$

the output is:

no

Hint: Use a loop and the isdigit$()$ function.