Explanation

By Decoding the given Sequence in the way $A\to 1;B\to 2;....Z\to 26$

$A,D,H,M,S\to 1,4,8,13,19$

The difference between two successive numbers is increasing by '1' starting from with '3'

$1+3=4$

$4+4=8$

$8+5=13$

$13+6=19$

$19+7=26$

Hence according to decoded language the next number is '26' i.e $Z$