Input:[3 1 2 5 3]
Output:[3, 4]
A = 3, B = 4

def repeated_number(number_array):

   pair_A_B = []

   n = len(number_array)

   for i in number_array:
      if(number_array.count(i)==2):
        pair_A_B.append(i)
        break

   sample = range(1,n+1)

   diff = list(set(sample)-set(number_array))

   pair_A_B.append(diff[0])

   return pair_A_B

sample_input = [3,1,2,3,5]

print(repeated_number(sample_input))