How to make a string == one string in a cell array

I need to make a chatbot for an assignment and im having trouble with this part of the script

 x = input('+ ', 's');
 if x == {'hey','hi','hello'};
    disp('Hello')

So if the user says hi, hey or hello, the script will print hello.

But when I type in, for example, 'hey' I get the error

Undefined function 'eq' for input arguments of type 'cell'.

Error in Bot (line 3) if x == {'hey','hi'};

Cheers

Answer 1

[Azzi Abdelmalek]

x = input('+ ', 's');
s={'hey','hi','hello'};
if ismember(x,s)
  disp('Hello')
end

Answer 2

[Walter Roberson]

   x = input('+ ', 's');
   if any(strcmpi(x, {'hey','hi','hello'})
      disp('Hello')
   end

You should avoid using "==" to compare strings. "==" will fail if the two strings have different lengths. Use strcmp() or strcmpi() instead