def solve():

count = 0

diff_l = []

real_work = []

for item in lift_movement:

if item!="-1":

real_work.append(int(item))

length = len(real_work)

if length == 1:

print(0)

else:

for i in range(1,length):

diff = real_work[i]-real_work[i-1]

diff_l.append(diff)

for item in diff_l:

if item<0:

count+=1

print(count)

testcases = int(input())

for i in range(testcases):

lift_movement = []

a =input()

n ,m = a.split(" “)

n , m = int(n), int(m)

question = input()

lift_movement = question.split(” ")

solve()

This is my code for The question Elevator. Can someone please tell where I am wrong. I removed -1 becuase they donot matter as long as we hav to find the minimum number of changes