Alternate Row Pattern

The program must accept an integer N as the input. The program must print the desired pattern as shown in the Example Input/Output section.

Boundary Condition(s):
1 <= N <= 26

Input Format:
The first line contains N.

Output Format:
The first N lines contain the desired pattern as shown in the Example Input/Output section

Example Input/Output 1:
Input
4

Output
ab
a
abcd
abc

Example Input/Output 2:
Input:
7
Output:
ab
a
abcd
abc
abcdef
abcde
abcdefgh

n=int(input())
k=2
a="abcdefghijklmnopqrstuvwxyz"
while(n>0):
print(a[:k])
n-=1
if(n>0):
print(a[:k-1])
n-=1
else:
break
k+=2