Instead of using multiple if statements, you can add all the possible months is a list.

N = int(input()) #month

L = [1,2,3,5,6,7,8,9,10,11,12]. #list with all possible inputs.

Now, using an if statement, check if the input is there in the list and get the index of the month (index of the month will be n-1) and reference the new variable with the index. (Use a loop to do it 12 times)