% https://open.kattis.com/problems/stopwatch
% 1s
% 1.5 Easy

% Picat
main :-
    [N|L] = read_file_lines().map(to_int),
    println(cond(N mod 2==1,"still running",w(L))).
main.

w(L) = S =>
  w(L,0,S).
w([],S,S).
w([T1,T2|Ts],S0,S) :-
    S1 is S0+T2-T1,
    w(Ts,S1,S).