s = eval(input())

n = len(s)

rs = sorted(s)

cnt = 0

ans = 'no'

for i in range(0, n-1):

    if rs[i] != rs[i+1]:

        cnt += 1

        if cnt == n-1:

            ans = 'yes'

            print(ans)

            exit()

print(ans)

s = eval(input())

rs = set(s)

if len(s) == len(rs):

    print('yes')

else:

    print('no')

s = eval(input())
n = len(s)
rs = sorted(s)
cnt = 0
ans = "no"
for i in range(0, n - 1):
    if rs[i] != rs[i + 1]:
        cnt += 1
        if cnt == n - 1:
            ans = "yes"
            print(ans)
            exit()
print(ans)

s = eval(input())
rs = set(s)
if len(s) == len(rs):
    print("yes")
else:
    print("no")

-n = len(s) -rs = sorted(s) -cnt = 0 -ans = "no" -for i in range(0, n - 1): -    if rs[i] != rs[i + 1]: -        cnt += 1 -        if cnt == n - 1: -            ans = "yes" -            print(ans) -            exit() -print(ans) +rs = set(s) +if len(s) == len(rs): +    print("yes") +else: +    print("no")