#include<iostream>
#include<cassert>
#include<atcoder/modint>
#include<atcoder/segtree>
#include<atcoder/lazysegtree>
using namespace std;
using mint=atcoder::modint998244353;
long long N,A,K;
int V[3<<17];
mint c[3<<17];
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cin>>N>>A>>K;
	if(N<K+K)
	{
		V[0]=0;
		c[0]=0;
		mint ans=0;
		for(int i=1;i<=N;i++)
		{
			V[i]=V[i-1]+A;
			c[i]=c[i-1]+(V[i]/K);
			V[i]%=K;
			ans+=c[i]*(i*2);
		}
		int cur=0;
		for(int i=N;i>=1;i--)if(V[i]>0)
		{
			if(cur==0)ans+=i*2,cur=V[i];
			else
			{
				cur+=V[i];
				if(cur>K)ans+=i*2;
				cur%=K;
			}
		}
		cout<<ans.val()<<endl;
		return 0;
	}
	V[0]=0;
	c[0]=0;
	int k=2*K;
	for(int i=1;i<=k+N%k;i++)
	{
		V[i]=V[i-1]+A;
		c[i]=c[i-1]+(V[i]/K);
		V[i]%=K;
	}
	assert(V[N%k]==V[k+N%k]);
	mint ans0=0,ans1=0,ans2=0;
	mint v=c[k+N%k]-c[N%k];
	{
		int cur=0;
		for(int i=k+N%k;i>N%k;i--)
		{
			//ans+=2*(c[i]+v*j)*(i+k*j);
			ans0+=2*c[i]*i;
			ans1+=2*c[i]*k+2*v*i;
			ans2+=2*v*k;
			if(V[i]>0)
			{
				if(cur==0)
				{
					//ans+=2*(i+k*j)
					ans0+=2*i;
					ans1+=2*k;
					cur=V[i];
				}
				else
				{
					cur+=V[i];
					if(cur>K)
					{
						//ans+=2*(i+k*j)
						ans0+=2*i;
						ans1+=2*k;
					}
					cur%=K;
				}
			}
		}
		assert(cur==0);
	}
	mint ans=0;
	int cur=0;
	for(int i=N%k;i>=1;i--)
	{
		ans+=2*c[i]*i;
		if(V[i]>0)
		{
			if(cur==0)ans+=i*2,cur=V[i];
			else
			{
				cur+=V[i];
				if(cur>K)ans+=i*2;
				cur%=K;
			}
		}
	}
	mint J=N/k;
	//ans+=sum_{j=0..J-1}(ans0+ans1*j+ans2*j*j)
	ans+=ans0*J;
	ans+=ans1*J*(J-1)/2;
	ans+=ans2*J*(J-1)*(2*J-1)/6;
	cout<<ans.val()<<endl;
}