A reversible prime in any number system is a prime whose "reverse" in that number system is also a prime. For example in the decimal system 73 is a reversible prime because its reverse 37 is also a prime.
Now given any two positive integers N (<105) and D (1<D≤10), you are supposed to tell if N is a reversible prime with radix D.
Input Specification:
The input file consists of several test cases. Each case occupies a line which contains two integers N and D. The input is finished by a negative N.
Output Specification:
For each test case, print in one line if YesN is a reversible prime with radix D, or if not.No
Sample Input:
73 10
23 2
23 10
结尾无空行
Sample Output:
Yes
Yes
No
结尾无空行
def change(x,d):#把十进制的x转换成d进制，并输出反转的d进制数的字符串
num = ''
while x:
num += str(x % d)
x //= d
return num
def decideprime(x):#判断是否为素数
if x == 0 or x == 1:
return False
for i in range(2,int(x**0.5)+1):
if x % i == 0:
return False
return True
while 1:
data = list(input().split())
if int(data[0]) < 0:
break
else:
a = int(data[0])
b = int(data[1])
k = change(a,b)
length1 = len(k)-1
S = 0
for i in k:#把反转后的d进制数转换成十进制数
S += int(i)*(b**length1)
length1 -= 1
if decideprime(a) and decideprime(S):
print('Yes')
else:
print('No')
Yes Yes No结尾无空行
def change(x,d):#把十进制的x转换成d进制，并输出反转的d进制数的字符串
num = ''
while x:
num += str(x % d)
x //= d
return num
def decideprime(x):#判断是否为素数
if x == 0 or x == 1:
return False
for i in range(2,int(x**0.5)+1):
if x % i == 0:
return False
return True
while 1:
data = list(input().split())
if int(data[0]) < 0:
break
else:
a = int(data[0])
b = int(data[1])
k = change(a,b)
length1 = len(k)-1
S = 0
for i in k:#把反转后的d进制数转换成十进制数
S += int(i)*(b**length1)
length1 -= 1
if decideprime(a) and decideprime(S):
print('Yes')
else:
print('No')
