BZOJ 4173: 数学 欧拉函数

#include<cstdio>
#include<cstdlib>
#include<ctime>
#include<cmath>
#include<cstring>
#include<string>
#include<algorithm>
#include<iostream>
#include<iomanip>
using namespace std;
const int mod=998244353;
long long phi(long long x)
{
long long re=x;
long long i;
long long t=x;
for(i=2;i*i<=x;i++)
{
if(t%i==0)
{
re-=re/i;
while(t%i==0) t/=i;
}
}
if(t!=1) re-=re/t;
return re;
}
int main()
{

long long n,m;
scanf("%lld%lld",&n,&m);
long long ans=phi(n)%mod*(phi(m)%mod)%mod*(n%mod)%mod*(m%mod)%mod;
cout<<ans<<endl;
return 0;
}