Hello people…can you please help me with this problem

i understood the algo…

if there exists atleast n-1 numbers such that they can be reduced to 0 , then through some mathematical caluculations we deduce that there must be only 2 distinct remainders (number % k+1 ) and that only one or none of the numbers should give a different remainder…

But is it necessary that if there are two distinct remainders then the numbers can be deducted to zero?? how will u prove this??