## Welcome To SDIBT ACM-ICPC Online Judge

VIRTUAL JUDGE Recent Contest F.A.Qs Discuss Home ProblemSet Status Ranklist 13 Contest LoginRegister Exam
2017 ACM 集训队预选排名~      报名入口
Problem 1063. -- Carmichael Numbers

## Carmichael Numbers

Time Limit: 1 Sec  Memory Limit: 64 MB
Submit: 16  Solved: 7
[Submit][Status][Discuss]

## Description

Certain cryptographic algorithms make use of big prime numbers. However, checking whether a big number is prime is not so easy. Randomized primality tests exist that offer a high degree of confidence of accurate determination at low cost, such as the Fermat test. Let a be a random number between 2 and n - 1, where n is the number whose primality we are testing. Then, n is probably prime if the following equation holds: an mod n = a If a number passes the Fermat test several times, then it is prime with a high probability. Unfortunately, there is bad news. Certain composite numbers (non-primes) still pass the Fermat test with every number smaller than themselves. These numbers are called Carmichael numbers. Write a program to test whether a given integer is a Carmichael number.

## Input

The input will consist of a series of lines, each containing a small positive number n ( 2 < n < 65, 000). A number n = 0 will mark the end of the input, and must not be processed.

## Output

For each number in the input, print whether it is a Carmichael number or not as shown in the sample output

```1729
17
561
1109
431
0

```

## Sample Output

```The number 1729 is a Carmichael number.
17 is normal.
The number 561 is a Carmichael number.
1109 is normal.
431 is normal.

```

## Source

UVA toolkit

[Submit][Status][Discuss]

HOME Back

한국어 中文 English
All Copyright Reserved 2008-2010 SDIBT TEAM
GPL2.0 2003-2010 HUSTOJ Project TEAM