% NOIP2018-J T3
% input

int: n;
int: m;
array[1..n] of int: T;

% description

int: upper_bound = max(T) + m;
int: max_times = min(max(T) div m + 1, n);
var 1..max_times: times;
array[1..max_times] of var 0..upper_bound: departure;

var int: object;

constraint forall(i in 1..times-1)(departure[i+1] - departure[i] >= m);
constraint object = sum(i in 1..n)(min(j in 1..times where departure[j] >= T[i])(departure[j] - T[i]));
% The shuttle bus departs from Renmin High School, drops off students at Renmin University, and then returns to Renmin High School (to pick up other students). This round trip takes a total of 𝑚 minutes (ignoring the time spent by students getting on and off the bus).

%solve

solve::int_search(array1d(departure), input_order, indomain, complete)
minimize object;

%output

output[show(object)];