Rotate Matrix Pattern

The program must accept an integer matrix of size N*N as the input. The program must rotate the matrix by 45 degrees in the clockwise direction. Then the program must print the rotated matrix and print asterisks instead of empty places as the output.

Boundary Condition(s):
3 <= N <= 100

Input Format:
The first line contains N.
The next N lines, each contains N integers separated by a space.

Output Format:
The first (2*N)-1 lines containing the rotated matrix.

Example Input/Output 1:
Input:
3
1 2 3
4 5 6
7 8 9

Output:
**1
*4 2
7 5 3
*8 6
**9 

Explanation:
After rotating the matrix by 45 degrees in the clockwise direction, the matrix becomes
  1
 4 2
7 5 3
 8 6
  9
So the rotated matrix is printed and the asterisks are printed instead of empty places.

Example Input/Output 2:
Input:
4
13 21 36 49
55 65 57 80
17 32 63 44
56 60 78 98

Output:
***13
**55 21
*17 65 36
56 32 57 49
*60 63 80
**78 44
***98

n=int(input())
arr=[]
for i in range(n):
   a=[]
   for j in range(n):
       a.append(int(input()))
   arr.append(a)
s1,s2=0,0
stars=n-1
for i in range(1, (2*n)):
   i1=s1
   i2=s2
   for j in range(1,n+1):
       if(j<=stars):
           print("*",end=' ')
       else:
           print(arr[i1][i2],end=" ")
           i1-=1
           i2+=1
   if(i>n-1):
       s2+=1
       stars+=1
   else:
       stars-=1
       s1+=1
   print("")