R=range
N,A,K=map(int,input().split())
L=2*K
r=N%L+1
q=N//L
t=0
a=sum((A*L*(2*q-1)*332748118+A*k//K*K+A*k)*(q-1)+A*k//K*k for k in R(r,r+L))*2*q
def U(X):
	global t,a
	b=t<1and A*k%K>0;t+=A*k%K;
	if t>=K:t-=K;b|=t>0
	a+=b*X
for k in R(r+L-1,r-1,-1):U((K*(q-1)+k)*2*q)
t=0
for k in R(r-1,-1,-1):U(2*k)
for k in R(1,r):a+=A*k//K*2*k
print(a%998244353)