### XX86's blog

By XX86, history, 4 weeks ago, ,

How Can I solve this problem!https://www.codechef.com/problems/COZIE Can anyone explain,please?

• -3

 » 4 weeks ago, # |   +3 If $A \times B = LCM(A,B)$ then $A$ and $B$ are coprime, or number of possible $B$ is $\phi(A)$ (where $\phi(x)$ is Euler's totient fuction) For $x \ge 3$ $\phi(x)$ is even, and $\phi(x) = 1$ for $x = 1$ or $x = 2$ but $1$ is not a prime number So the only possible prime value for $\phi(x)$ is $2$ You should find all values $x$ for which $\phi(x) = 2$ and spot them among given $N$ numbers
•  » » 4 weeks ago, # ^ |   0 For x≥3 ϕ(x) is even, and ϕ(x)=1 for x=1 or x=2 but 1 is not a prime number So the only possible prime value for ϕ(x) is 2. oh!yeah.thanks!