Thanks kiddo, I'm now almost in the solutin. there is little thing to correct.
Code:

N = int(input("N: "))
i=1
Sum1=0
Sum2=0

while i <= N:
   
    if i%2==0:                                              #If i is even
           print("-",i, end=' ')
           Sum1=Sum1+i
    else:                                                  #if i is odd
           print("+", i, end=' ')
           Sum2=Sum2+i
    i=i+1
   
print("=", Sum2-Sum1)

Result:
N: 5
+ 1 - 2 + 3 - 4 + 5 = 3
>>> ================================ RESTART ================================
>>>
N: 3
+ 1 - 2 + 3 = 2
>>> ================================ RESTART ================================
>>>
N: 4
+ 1 - 2 + 3 - 4 = -2

How to remove + sign before 1
should look like this
1-2+3-4=-2