rev string by not affecting spcl char.python

n = str(input())
m=list(n)
r=len(m)-1
l=0
while(l<r):
    if not m[r].isalpha():
        r-=1
    elif not m[l].isalpha():
        l+=1
    else:
        temp=m[r]
        m[r]=m[l]
        m[l]=temp
        l+=1
        r-=1
print(''.join(m))