why doesn't my if check work, characther comparisasion [duplicate]

a = input("input a name ")
print("your name is: ",a)
print(a[-1])
if a[-1] == "e" or "a":
    print(a, "there is either a e or a in the name")
    print(a[-1])
elif a[-1] == "s":
    print(a,"there is s ")
else:
    print(a,"there isnt e or a in the name")

Dont understand what I am doing wrong, no matter what u input it will always get stuck on the first if statement