a = list(input());b = set(a);print("yes") if(len(a)==len(b)) else print("no")

a = list(eval(input()));print(("yes" if(len(a)==len(set(a))) else "no"))

a = list(input())
b = set(a)
print("yes") if (len(a) == len(b)) else print("no")

a = list(eval(input()))
print(("yes" if (len(a) == len(set(a))) else "no"))

-a = list(input()) -b = set(a) -print("yes") if (len(a) == len(b)) else print("no") +a = list(eval(input())) +print(("yes" if (len(a) == len(set(a))) else "no"))