BZOJ4173 数学

标签：欧拉函数，数学，数论

Description

 

Input

 输入文件的第一行输入两个正整数 。 

Output

 如题

Sample Input

5 6

Sample Output

240

HINT

 N,M<=10^15

 

直接放PoPoQ大爷的式子

http://blog.csdn.net/popoqqq/article/details/46820313

code

#include<cstdio>#include<iostream>#include<cstring>#include<cstdlib>#include<cmath>#include<algorithm>#define rep(i,a,b) for(LL i=a;i<=b;i++)#define dep(i,a,b) for(LL i=a;i>=b;i--)#define LL long long#define mem(x,num) memset(x,num,sizeof x)using namespace std;const LL mod=998244353;LL n,m;LL phi(LL n){LL t=n;rep(i,2,sqrt(n))    if(n%i==0){t=t/i*(i-1);while(n%i==0)n/=i;}if(n!=1)t=t/n*(n-1);return t;}int main(){cin>>n>>m;cout<<(phi(n)%mod)*(phi(m)%mod)%mod*(n%mod)%mod*(m%mod)%mod<<endl;return 0;}