Let us imagine there are four 0’s, so the number should be 40000, but this violates that the 5th digit tells how many 4’s are there.
Now let us imagine that there are three 0’s then the number can be 30010, but this also violates that the 2nd digit tells the number of 1’s
Now if there are two 0’s then 21200 satisfies all the conditions.
Thus, your answer is 21200
Hope i helped you! :)