You have 50 employees, each of whom within their 9 hour day are entitled to
one 30 minute break and two 15 minute breaks, hence a total of one hour
within the 9 hours.  On average, therefore, you would have 50/9 (or 5.5555)
employees on a break at a time.
What constraint is there on how long a gap there is between breaks (or
between a break and the start or end of the day)?
What constraint on what order the beaks are taken in (in other words is it
always a 15 minute break in the morning, then a 30 minute in the middle of
the day, then another 15 minute break in the afternoon?)?
Any constraint on which employees are on a break together, or all 50
regarded as interchangeable for this purpose?
Not clear what you mean by "no 2 empolyees breaks are same". Do you mean
that if employee A goes for a break starting at 10:15, employee B can't go
until 10:16, or until 10:15:01, or what do you mean?  [You said "if 1
empolyee is on lunch break for 30mins, the other employee will go for break
after other returns", but we've already established that an average of more
than 5 will be on a break at the same time.]

As you see, still many more questions than answers.  You really need to
specify the problem much more precisely before you come to the group for
help.  With most computing problems, it isn't the implementation of the
solution that is the difficult part of the task, but the specification of
the requirement.